An initial DNA test on remains believed to be those of Joseph Couch, the suspect in the Interstate 75 shootings, was inconclusive, but an autopsy confirmed the cause of death was a self-inflicted gunshot wound, state officials said.

The soft tissue DNA test was “inconclusive due to extreme decomposition of the body,” and a further DNA test with material extracted from bone will be completed, the Kentucky Justice and Public Safety Cabinet said in a news release.

Couch, 32, a former Army reservist, had been the subject of a manhunt after five people were shot and seriously wounded as they drove on Interstate 75 north of the small city of London on Sept. 7.

Authorities said he had texted someone about 30 minutes before the shootings and wrote, “I’m going to kill a lot of people. Well try at least.”

At least 12 vehicles were struck, and 20 to 30 rounds are thought to have been fired, officials said.

The remains were found in deep brush by a highway exit in Laurel County, which is where London is and where the shootings occurred, state officials said.

“At this time, we are able to confirm that the autopsy revealed the cause of death to be a wound consistent with a self-inflicted gunshot to the head,” the state chief medical examiner, Dr. William Ralston, said in a statement.

A couple livestreaming the search for Couch's body helped in the effort and the discovery, state police said. Vultures had been circling the body. Personal articles and a gun around the body led investigators to believe it was Couch’s, State Police Col. Phillip Burnett Jr. said.

The couple, Fred and Sheila McCoy, said they have been told they'll receive a $25,000 reward that was offered during the manhunt.

The DNA test from bone is expected to begin Friday and take 24 to 48 hours, the Justice and Public Safety Cabinet said.