It's the morning of Jan. 26, 2022. Sarah Harris, 25, lies unresponsive on the floor of the home she shares with her boyfriend, 48-year-old Dr. James Ryan. She is found in the living room, which is in disarray. Ryan tearfully talks with Montgomery County, Maryland, police at the scene. The conversation is recorded on a body camera as they ask him about the night before:

FIRST RESPONDER (bodycam video): Was she sleeping on the couch last night?

DR. JAMES RYAN: Yes. She would do that sometimes (crying).

DR. JAMES RYAN (bodycam video): We were watching TV and then she said you should probably go to bed because you're tired and you have to work tomorrow … so I did …(crying).

FIRST RESPONDER: Uh huh. What time did you go to bed?

DR. JAMES RYAN: …Probably about 10 or 11 (crying).

Ryan has already told authorities he's a doctor, and that he thinks it's an overdose. And he says it's happened before.

DR. JAMES RYAN (bodycam video): … and I did CPR and brought her back.

This time, Sarah doesn't survive. Ryan has suggested where she got at least one of her drugs of choice — a powerful anesthetic.

JAMES RYAN (bodycam video): She used to take propofol too, she used to steal that from my office.

How they got into her body and why.

JAMES RYAN (bodycam video): I've caught her before with, um, like injecting herself with things.

JAMES RYAN (bodycam video): She was bipolar also, so she could be really angry or could be really happy.

THE DEATH OF SARAH HARRIS

Ryan had called Sarah's family with the awful news that morning. But her mother, Tina Harris, just didn't believe anything he said. She immediately suspected Ryan was responsible for Sarah's death. She arrived at the scene about 20 minutes later.

Tina Harris: I started kicking and hitting him and screaming at him.

Nikki Battiste: What did he say happened?

Tina Harris: He said he went to bed and left her alone and came down and she was unresponsive in the morning.

Authorities say they found wrappers from syringes, tourniquets and saline bags next to the kitchen sink, and drug vials in Sarah's purse. Tina Harris thinks Ryan arranged it that way.

Tina Harris: He wanted it to look like it was a suicide.

Tina Harris had long held suspicions about Dr. Ryan. He had encountered Sarah Harris more than a year earlier — not as a girlfriend, but as a patient to get her wisdom teeth out.

Mary Fulginiti is a former prosecutor and defense attorney and a CBS News consultant. "48 Hours" asked her to use her decades of courtroom experience to help analyze this case.

Mary Fulginiti: Dr. Ryan is somebody who's practiced for over 20 years. … He has incredible credentials. He's esteemed and regarded in his community as one of the best at what he does.

Tina Harris says the first time her daughter met Dr. Ryan for her teeth in the summer of 2020, the doctor was professional. But she does remember at the time feeling it was curious when his interest in Sarah seemed to change.

Tina Harris: She starts getting all these text messages. … He asks her, "how are you doing?" And she says, "I'm fine." And he starts sending little emojis.

Nikki Battiste: What are you thinking as her mom?

Tina Harris: I thought it was a little bizarre that he added a little happy face and … I thought, well, maybe he just likes using emojis.

She says that's when Ryan had mentioned he was looking to hire someone as a surgical assistant.

Tina Harris: I thought, well, you know, maybe he just thinks that she'd really be a good addition.

Ryan hardly seemed like a threat. He was divorced with three grown children and was involved with a woman with whom he already had a baby. At 47, he was more than twice Sarah's age.

Tina Harris: He said, "no, I don't need your resume. … just come on in for a working interview." … I said, "well, I'm proud of you, honey. That's pretty incredible. … that he's gonna teach you all this stuff."

At the beginning, Sarah seemed to love the job, but Tina Harris says as the holidays approached, an extravagant gift – a diamond necklace — retriggered her suspicion that Ryan's interest in Sarah was more than professional.

Tina Harris: I said, "OK, he's after you." I said, "you gotta put your foot down."

Instead, in early 2021, she says Sarah announced she had agreed to go out for a meal with Ryan, who was ending his other relationship. He seemed to win over Sarah. Tina Harris admits, in their early days as a couple, even she found him impressive.

Nikki Battiste: As a mother, was a part of you excited, she's — dating a doctor?

Tina Harris: Oh, well, I was excited! I was excited because… he had a wonderful reputation.

And she says Ryan was generous. He would lease Sarah a new car and take her and her family on trips — all expenses paid. Tina Harris says, in a way, he spent time courting her, too.

Tina Harris: He would say, "I would love to have you as my mom. Sarah's so blessed to have you."

Tina Harris says she and Sarah always had a special bond.

Tina Harris: We were very, very close.

She says Sarah was close to her three siblings, too — especially older sister Rachel Harris.

Tina Harris: Rachel … took it upon herself that she was gonna be the protector.

But there had been a rough period during Sarah's youth in suburban Maryland. Like many young people, she experimented with drugs, and had problems moderating her mood. She suffered from anxiety.

Nikki Battiste: When did she first struggle with depression?

Tina Harris: I noticed depression coming about when she was about 14, 15 years old. She would start feeling down.

But Tina Harris says Sarah still exceled in high school — craving knowledge and the skills that came with it. She learned German, Spanish, Russian and American Sign Language.

Tina Harris: She put a lot of pressure on herself … especially with her grades.

Before long, Sarah got her social bearings.

Tina Harris: She fell into a great group of kids … They would sit down in the living room and play the guitar, play the piano, sing.

She was at a music festival in 2018 when 21-year-old Sarah caught the eye of Henry Peterson, seven years older.

Henry Peterson: I feel like it was like stars colliding and, meeting someone like you're supposed to meet.

They lived seven hours apart, but he says they quickly became emotionally inseparable.

Henry Peterson: We talked about everything you could think of in terms of a future … marriage and children and family.

He says the distance eventually made them drift. Peterson broke it off, though he says he still imagined they would end up together.

Henry Peterson: She and I never stopped talking. The love was always there.

By her mid-20s, Sarah had gotten into modeling and competing in beauty pageants. In 2020, she'd won the Miss Maryland Petite Pageant. The next year is when she started quietly seeing Ryan, and by that summer, they had decided to live together.

Tina Harris: And that's when everything goes downhill.

WAS DR. RYAN OBSESSED WITH SARAH HARRIS?

By the end of the summer of 2021, Tina Harris says James Ryan was dominating Sarah's life: Boss, boyfriend — even letting her live rent free in his house. But instead of flourishing, Sarah seemed anxious and depressed. She saw a psychiatrist, who gave her that bipolar diagnosis.

Tina Harris: Her complexion starts to change … She starts to lose weight.

On a family trip to Key West that September, Tina Harris says Sarah had been asleep when a drunk Ryan revealed something unsettling: he had first noticed Sarah when she was just 14.

Tina Harris: "I used to see Sarah walking the neighborhood and playing at the park with her friends."

Tina Harris: And he says … "then I found out she worked in the toy store … so I would take my kids there so I could see her and I remember when she dressed up as Elsa from 'Frozen' and she looked just like Elsa" … and then he said, "yeah and then I found out she worked at one of these restaurants and so I would go in there for dinner so I could get her as my server."

Nikki Battiste: It sounds like Doctor Ryan was obsessed with Sarah.

Tina Harris: He was. He was very much so.

By their next trip to Florida a month later, she says Sarah was acting strangely. She wore a bulky long-sleeved sweatshirt despite the heat. And it seemed like she and Ryan were always fighting.

Tina Harris: And she goes," I hate him. … I don't wanna be here. I wanna go home."

And when they returned to Maryland, Tina Harris saw the full horrifying picture of what Sarah's life had become. She says she called Sarah on Oct. 28, 2021.

Tina Harris: Phone rang, rang, rang, she finally picked up. She could barely talk. Her words were extremely slurred. So, I said, "Sarah what's going on? What's wrong with you?" She goes, "Oh, I'm just really tired mom."

Nikki Battiste: You knew something was wrong.

Tina Harris: Yeah. Well, I knew she was slurring.

Tina Harris says she and Rachel left for Sarah's house minutes later.

Tina Harris: And we walked into hell.

Nikki Battiste: What did you see?

Tina Harris: Well, Sarah answers the door … she smells, it looks like she hadn't bathed in a week or more. She looked horrible.

She'd weighed 120 pounds when she'd had oral surgery with Ryan, Tina Harris says. But Sarah was skin and bones now. And Tina says there was more.

Tina Harris: The IV bags, needles laying all over the floor … syringes, tourniquets, bloody footprints, bloody paper towels …

And there were drugs, bottles and vials everywhere. Rachel gathered them up and photographed them.

Tina Harris: I never looked at the drugs and I wish I had.

Nikki Battiste: Do you think some people watching would think, how did you not look at what the drugs were?

Tina Harris: Of course … I just wanted to get her out.

She says Sarah had offered an innocent, if unconvincing, explanation.

Tina Harris: She goes, "I've just been dehydrated, mom. … he's just hydrating me."

Tina Harris: I said, "I'm turning him in." … And Sarah starts crying, "mom you can't do that. Please don't do that." She's begging me … I grabbed her arms and I pulled her sleeves up, and she had needle marks from here to here (moves her hand from her wrist to her elbow), all over her arms, bruises … I became hysterical.

Against her better judgment, Tina Harris agreed to hold off on calling authorities. But she says she insisted Sarah move back home. Just days later, Tina says Ryan convinced Sarah to come back to him.

In the following weeks, Tina Harris says Sarah seemed to be getting better. She started cooking, eating and even going to church. But on Dec. 3, 2021, Tina says her daughter answered the phone slurring again. Rachel Harris jumped into action.

Tina Harris: Rachel said … "I'm gonna go and check on her."

When Rachel got there, Tina says "It was worse than the first time."

Poking around the ground floor, Rachel Harris once again pulled out her camera, finding drug bottles and vials, as well as a saline bag, an IV pole, IV needles and bloody footprints on a kitchen mat. She was so distraught, she left without talking to her sister. A few days later, Tina Harris confronted Dr. James Ryan. She was in no mood for another explanation.

Tina Harris: I just reached across and smacked the living crap out of him.

Nikki Battiste: You hit him?

Tina Harris Yeah. Oh, I hit him, and I said, "what are you doing? Are you trying to kill my daughter?"

Tina Harris says Ryan still insisted he'd only been hydrating her.

Nikki Battiste: And you still believed it?

Tina Harris: I believed he was giving her something. I didn't know what it was. I did not look at the vials … All I could see was my daughter and what kind of trouble she was in.

But the next day she says Ryan admitted he'd been doing more than hydrating her. He'd been giving Sarah drugs — though only, he said, to keep her from getting them someplace else.

Tina Harris: So, I told him — I said, "look … you can break it off with my daughter … Or I'm calling the police …" And he said, well, I'll break it off with her.

But days turned into weeks and Ryan never did. After months of tension, Tina Harris says she couldn't keep arguing with her daughter anymore.

Tina Harris: What was I gonna do, lock her up?

Nikki Battiste: You probably wanted to.

Tina Harris: I threatened it and she said, "if you do that, mom, when I get out, you'll never hear from me again," and that scared me to death.

Within weeks, there was a new tragedy for the Harris family. Sarah's brother Christopher, just 38, died after a heart attack in Montana.

Tina Harris: I had to sign the papers to take him off life support … which no mother should have to do.

His death was devastating to the whole family. Sarah posted this tribute message to her brother:

"Never goodbye. I'll see you soon big bro." And only 18 days after Christopher's death, at about 8:30 a.m. on Jan. 26, 2022, Tina Harris says she and Rachel were together when Rachel got James Ryan's call.

Tina Harris: Rachel started screaming … she's holding the phone and James has it on Facetime and he's got the camera pointed at my baby, had Sarah on the ground, saying, "she's gone, she's gone."

At the time of her death, Sarah weighed just 83 pounds. Authorities would list her manner of death as undetermined. Ryan was not arrested. They seemed to accept his story that Sarah, struggling with mental health issues, had overdosed. But there would be help from a most unlikely investigator.

A SISTER'S SEARCH FOR CLUES

Three months before she died, Sarah left a voicemail for her ex-boyfriend Henry Peterson.

SARAH HARRIS (voicemail): I just hope that you're happy that I'm with someone who truly, truly loves me …

SARAH HARRIS (voicemail): I've never trusted anybody as much as I've trusted the man that I'm with right now professionally, emotionally … you never let me in that way. …

They'd stayed in touch after breaking up, so when she didn't answer her phone after January 2022, Peterson says he had a strange feeling and decided to go online.

Henry Peterson: I Googled her name, and — there's an obituary.

Peterson says when Tina Harris gave him details, he joined her in the belief that James Ryan — the man Sarah said she had trusted more than anybody else — was responsible for her death. But first responders didn't think so.

Tina Harris: They didn't shut it down as a crime scene.

Police seized some drug vials but left the house unguarded. Tina Harris says that's because they believed what Ryan had told them about where Sarah had gotten the drugs and how she'd taken them.

Tina Harris: It was an … overdose …

But Tina Harris says she knew there was more to it than that — though she didn't know how to prove it. Turns out, there was someone very close to her who did.

Tina Harris: Rachel told me she would find the evidence.

Rachel Harris decided to examine Sarah's laptop, to see if it might contain clues authorities hadn't seen. She didn't know the password, but she knew her sister well.

Tina Harris: It took her about a couple of days to figure out Sarah's password.

Combing through Sarah's computer and iCloud, Rachel Harris hit paydirt: a trove of texts between her sister and James Ryan. The messages were full of references to drugs, including a tranquilizer named diazepam and two fast-acting surgical anesthetics — the type Rachel had seen in the home Ryan and Sarah shared — propofol and ketamine, which is sometimes also used for depression. Rachel created a binder, adding the photos she'd taken there.

Nikki Battiste: Rachel compiled 200 pages of evidence —

Tina Harris: Mm-hmm.

The medical examiner would release Sarah's autopsy report, which showed those same three drugs in Sarah's system. Research suggests they can all be habit forming and they can suppress breathing. Taking them in combination can be lethal.

Nikki Battiste: All the while, Rachel's building a case?

Tina Harris: Yes, yes, yes.

In February 2022, Rachel Harris gave her binder to Montgomery County Police. It eventually landed on the desk of Detective Ian Iacoviello, an expert in pharmaceutical investigations. After more than 33 years as a cop, Iacoviello was nearing retirement. He decided to come in alone on a Sunday.

Det. Ian Iacoviello: It was my birthday, and nothing was going on. You don't get parties when you're this age. I'm like, I'm just gonna go in the office and look through this binder and just see.

What Iacoviello saw in Rachel Harris' binder suggested cops at the scene had been wrong about Sarah's death. He says reading the texts between Sarah and James Ryan was like watching a murder in slow motion.

Det. Ian Iacoviello: You could see … Sarah die.

Sarah is suffering within the first month of their relationship.

Det. Ian Iacoviello: She had … anxiety. She was having trouble sleeping.

Ryan offers a quick fix, "I can give you an injection … the anxiety will be completely gone in 6 second s [sic] …" He writes, "It will work. Let's try it …"

Det. Ian Iacoviello: He had already made the decision.

Iacoviello says, the texts suggest that over the months, Sarah developed a drug habit – and a habit of asking her boyfriend the doctor to feed it:

In October 2021: "do we have ketamine here" In November: "we need syringes … I feel like s***."

In December: "I just really need … sleep" she writes. "xan (sic) you bring propofol"

Det. Ian Iacoviello: She's actively asking for drugs. At no point, does he say no.

Iacoviello says the texts suggest Ryan often brought Sarah the dangerous drugs and that he actually administered at least one about a month before her death. It was Dec. 20, 2021. "If you wake up… I just went [sic] change after I gave you ketamine. Just now.…" he writes.

Det. Ian Iacoviello: He's injecting her while she's asleep. No monitoring, no anything.

And Iacoviello points to this exchange from the day before Sarah died. "Is it possible to bring home ketamine when you come…" she asks. "Yes, I will bring some home. I love you baby," Ryan replies.

Nikki Battiste: The texts tell a story.

Det. Ian Iacoviello: They do.

So do Rachel's photos from Sarah's house, says Iacoviello, though his colleagues lacking experience in pharmaceutical investigations might not have understood that.

Det. Ian Iacoviello: They had no idea what they were really looking at.

He says patrol cops and paramedics often deal with overdoses of street drugs like heroin and fentanyl. But the deadly drugs in Sarah Harris' house were masquerading as something else.

Det. Ian Iacoviello: There's a difference between drugs and medication.

Iacoviello says, to the untrained eye, the drugs at Sarah's looked like "medication." The paraphernalia around the house might have been confusing, too.

Det. Ian Iacoviello: Usually what we see is burnt spoons, tinfoil, um, some hypodermic needles … maybe a shoelace or some other string … that kind of drug paraphernalia …

But to Iacoviello, the syringes and the saline, the professional tourniquets and the plastic wrappers at Sarah's made it resemble an operating room.

Det. Ian Iacoviello: That's what a lot of it looked like.

Whatever questions responding authorities may have had, he says Ryan offered answers.

Det. Ian Iacoviello: And you've got James saying … she did all of this. Without any other information, OK, well, we're just kind of gonna go with what he says.

Nikki Battiste: He's a doctor.

Det. Ian Iacoviello: He's a doctor.

But Iacoviello says after reading through the family's binder, any credibility Ryan may have had that day vanished. And on March 22, 2022, nearly two months after Sarah's death, James Ryan was arrested for the murder of Sarah Harris. But prosecutors would have to make the case to a jury.

Prosecutor Jennifer Harrison: Sometimes it's hard to convince them.

Maybe especially so in this case, because Ryan's defense is suggesting he was only trying to save Sarah's life — and that she had other ideas.

WHAT IS "DEPRAVED-HEART" MURDER?

"I knew the case was solid, " says Iacoviello. He was sure Dr. James Ryan was responsible for Sarah Harris' death and he had no problem convincing prosecutors on Montgomery County's Overdose Taskforce: Jennifer Harrison, James Dietrich and Kimberly Cissel.

Prosecutor Jennifer Harrison: It's his fault.

Prosecutor James Dietrich: He was the one who was providing those drugs.

Prosecutor Kimberly Cissel: He knew how dangerous these drugs were.

Ryan was a doctor after all. But as certain as prosecutors were, that he knew he was risking Sarah's life, they had no conclusive evidence he intended to kill her.

James Dietrich: We never suggested that. … you can accept that James Ryan loved Sarah Harris … but it does not excuse all the other actions that he took that led to Sarah's — Sarah's death.

So they charge Ryan with a sub-category of second-degree murder unfamiliar to many people. It's known as depraved-heart murder. Prosecutors say the charge doesn't require proving the killer actually wanted anyone dead — only that they knew their actions would likely kill someone and didn't care.

Prosecutor Jennifer Harrison: We have to prove … that he did it with … reckless disregard for the value of her life.

Dietrich gave "48 Hours" an example.

Prosecutor James Dietrich: If I take a gun and just randomly shoot it into a crowd, I may not necessarily want or care that anybody dies. … But … that is such a grossly reckless act that someone's likely to die.

Prosecutors also charge Ryan with a slightly lesser charge, involuntary manslaughter, plus two counts of drug distribution and one count of possession with intent to distribute.

Opening statements begin on August 16, 2023. There are no cameras in court but there is an audio recording.

PROSECUTOR JENNIFER HARRISON (in court): Behind closed doors he was conducting a deadly medical experiment on his 25-year-old patient-turned-employee turned live-in girlfriend.

The prosecution portrays Ryan as a controlling older man who got his glamorous young girlfriend hooked on drugs.

PROSECUTOR JENNIFER HARRISON (in court): He was stealing dangerous sedation drugs from his business and administering them to his girlfriend Sarah Harris.

Prosecutors say the proof of Ryan's guilt is largely in those text messages: Ryan offering to get rid of Sarah's anxiety in six seconds, telling her he gave her ketamine while she was sleeping, and on the night before her body was found, apparently agreeing to bring ketamine home to her.

PROSECUTOR KIMBERLY CISSEL (in court): Can you tell us about Sarah? What was she like?

TINA HARRIS: Mm-hmm. I don't know where to start.

TINA HARRIS (in court): She was my baby (crying).

Tina Harris, who was the first to testify, is emotional as she relives Sarah's downward spiral just months before dying.

TINA HARRIS (in court): I asked to see her arms. And she said, "no, mama." But I grabbed her arms and I pulled up the sleeves and her little arms were covered in needle marks and bruises (crying).

And the medical examiner tells the jury about the dangerous drug cocktail that brought her life to a tragic end.

MEDICAL EXAMINER (in court): When people use … all three together, those just … cause profound strong sedation ...

The drugs can be so dangerous, in fact, the prosecution tells jurors that doctors who use these drugs have equipment and protocols in place to revive patients if needed.

Prosecutor Jennifer Harrison: Even though Dr. Ryan would follow all of those safety protocols in his own office, he would never follow those … at home.

Nikki Battiste: She was chemically dependent on him.

Janice Miller: She was chemically dependent on him.

Prosecutors also call social worker Janice Miller who says that kind of power imbalance is a hallmark of abusive relationships.

Janice Miller: The drugs were the way that he controlled her and really ensured that she wouldn't leave the relationship …

Det. Ian Iacoviello: He's created an addict.

Dr. Ryan and his attorneys did not agree to be interviewed by "48 Hours." But at trial, they argue Sarah Harris may have played an important role in her own demise; suggesting that after wrestling with mental illness, she was now losing her battle with anxiety, depression and drugs.

Mary Fulginiti: Their focus on Sarah Harris is obviously her mental illness …

The defense suggests Sarah may have begun stealing the drugs herself. They want the jury to know about her Facebook post about seeing her deceased brother "soon," but the judge won't allow it. But they are allowed to tell jurors about a text Sarah sent Ryan months before her death.

DEFENSE ATTORNEY (in court): She says "… I've lost my will to live …"

Nikki Battiste: Do you think there's any chance Sarah was suicidal?

Tina Harris: Absolutely not. Absolutely not.

Det. Ian Iacoviello: Where's the indication of a suicide on the scene? There is none.

Iacoviello says the drug bottles found in Sarah's purse were too far from her body for her to have given them to herself.

Det. Ian Iacoviello: These drugs are fast acting … She's gonna be out in seconds. … how she … put all the medication in her purse … then went and lay down, not possible.

Prosecutor James Dietrich: She wouldn't have cleaned up .. Somebody else had to have done it.

But according to CBS News consultant Mary Fulginiti, the defense argues that detectives mishandled the scene; that there's no way to know exactly what happened, including who administered the fatal dose.

Mary Fulginiti: They didn't test … to see if his DNA or fingerprints were on those syringes.

Ryan chooses not to testify. The defense argues he was a loving partner who was just trying to help Sarah.

Mary Fulginiti: This is a case about … caring for somebody … and — and possibly loving them to death.

His lawyers call a friend who saw Sarah using drugs before she began dating Ryan, and a relative who saw them as a happy couple.

In closings, prosecutors remind the jury that to convict Ryan of depraved-heart murder, it doesn't matter whether or not he actually put the drugs in Sarah's body…or even whether or not he wanted her to die.

Prosecutor Jennifer Harrison: … the act of giving her the drugs is … --him handing her a loaded gun …

But would the jury agree?

THE VERDICT

For as long as Kyle Stevens can remember, his friend Dr. James Ryan has done right by people.

Kyle Stevens: He was pretty straight lace, clean-cut … guy.

Nikki Battiste: When he talked about Sarah, how did he sound?

Kyle Stevens: In the beginning … he … seemed enthusiastic and excited.

But Stevens says at a certain point, Ryan did reach out with a concern.

Kyle Stevens: He had asked about how to best be helpful and supportive to someone … in that place of depression and possibly addiction.

Nikki Battiste: Did it make you wonder if he was actually asking about Sarah?

Kyle Stevens Yeah. … but I didn't press.

So Stevens says he had no idea what was really going on between the two. Then he discovered his friend was arrested and headed to trial.

Nikki Battiste: When you heard the verdict — what did you think?

Kyle Stevens: I was … taken back.

After a nearly two-week trial, it takes jurors less than three hours to reach their decision.

On Aug. 25, 2023 they find James Ryan guilty of the second-degree depraved-heart murder of Sarah Harris.

Prosecutor Kimberly Cissel: Relief.

Prosecutor Jennifer Harrison: Yeah. Relief.

They also convict Ryan on the manslaughter and drug charges.

Tina Harris: … my heart just felt satisfied …

Tina and Rachel Harris speak at a press conference after the verdict.

RACHEL HARRIS (to reporters): She was this beautiful beauty queen and she wasted away at the hands of Dr. James Ryan.

And again at Ryan's sentencing months later.

RACHEL HARRIS (in court): He is a predator. He is a wolf in sheep's clothing.

TINA HARRIS (in court): Please! (crying) … Put him behind bars, until his life is done.

But James Ryan's lawyers had submitted supportive letters from his friends and a legal filing which detailed that Ryan had his own struggles with drugs and mental health. Ryan addresses the court and insists he didn't administer the lethal dose but takes responsibility for not preventing Sarah's access to the drugs that killed her.

JAMES RYAN (in court): The words do not exist to convey and express the level of remorse I feel.

Though the guidelines suggest a sentence of 15 to 25 years for this case of depraved-heart murder, the judge has something else in mind.

JUDGE: It is the sentence of this court that you be committed to the Maryland Division of Corrections for a period of 40 years. …

With more time for the other counts, it's a total of 45 years in prison.

Nikki Battiste: A 45-year sentence puts James Ryan in a category with some violent murderers.

Mary Fulginiti: You know, 45 years for James Ryan is basically life … Patients rely on doctors and their expertise and their advice. … and I think she's sending a very loud message to the medical community.

And State's Attorney John McCarthy wants to send a message to lawmakers: The depraved-heart murder charge may have worked in this trial, but it's a difficult crime to prove in other overdose cases.

John McCarthy: We need tougher laws.

As early as 2015, McCarthy began pushing to streamline Maryland law so state prosecutors can more easily convict dealers and distributors who supply the drugs that lead to overdose deaths. But it hasn't been easy.

John McCarthy: We're not at a place in Maryland right now that the legislature seems very interested in creating new crimes and new penalties.

Ian Iacoviello, who read "murder" between the lines of this case, and retired after the trial, says he still thinks of Sarah often.

Det. Ian Iacoviello I did everything I could, um, for her.

So does her ex-boyfriend Henry Peterson, who looks back at their breakup with regret.

Henry Peterson: I guess I always thought she was gonna be there.

A regret Sarah seemed to share. Peterson showed "48 Hours" a letter she wrote him years earlier when their relationship ended.

Henry Peterson (reading letter): You made me feel alive … now that you're gone … I feel so many pieces and parts have died with you ...

As if to preserve his connection to Sarah, Peterson still practices a violin concerto he played at her grave.

It's the place where, today, a mother who faced great loss — with even greater courage — struggles to face the future without Sarah and her brother, who were so close in life and death, that she actually buried their ashes in the same casket.

Tina Harris: I hear Sarah telling me, "mama, it's OK."

Nikki Battiste: What do you want your daughter's legacy to be?

Tina Harris: I want people to remember my Sarah as a light, a brilliant young woman who cared about others and loved life, loved it.

James Ryan will likely be eligible for parole in 20 years. He is appealing his conviction.

Produced by Josh Yager and Kat Teurfs. Michelle Sigona and Tamara Weitzman are the development producers. Atticus Brady, Gary Winter, Michelle Harris and George Baluzy are the editors. Patti Aronofsky is the senior producer. Nancy Kramer is the executive story editor. Judy Tygard is the executive producer.