An autopsy on a 19-year-old man who died in the back of a jail transport van in Indiana found no signs of trauma, investigators said Tuesday.

The cause of death for Kyler L. Myers remains undetermined pending results of toxicology tests that could take up to six weeks, Indiana State Police Capt. David Bursten said at a news conference.

Myers was being held in the Johnson County Jail when he became agitated and a jail nurse told staff to take him to Johnson Memorial Hospital across the street. He died Monday after being found unconscious in the van that had taken him from the jail to the hospital.

"There is nothing that indicates any wrongdoing by members of the Greenwood Police Department and ... the Johnson County Sheriff's Department," Bursten said, explaining the evening news conference was called in part to quash any speculation of such wrongdoing in light of the recent death of Freddie Gray in Baltimore police custody. Six Baltimore police officers have been charged in Gray's death.

Myers was being held at the jail on preliminary charges of reckless possession of paraphernalia and disorderly conduct.

Greenwood police had arrested him early Monday after he called to report a possible burglary and asked officers to search his home, Bursten said. During the search, officers found drug paraphernalia. Myers was under house arrest at the time.

A Greenwood police report says Myers told officers had taken synthetic marijuana, the Indianapolis Star reported.

A jail nurse told staff to take Myers to the hospital after he "became increasingly agitated with other inmates" and "displayed unusual behavior," state police said in a news release.

Myers walked into the transport van on his own, Bursten said.

State police will forward the results of their investigation to the Johnson County Prosecutor's Officer once it's completed, Bursten said.