A 19-year-old Long Beach man who died in Los Angeles County Jail while awaiting trial on murder charges overdosed on fentanyl, according to a recently released autopsy from the Los Angeles Medical Examiner’s Office.

Kamren Nettles was being held at Men’s Central Jail on charges he caused the death of a Wilson High School student who was helping him rob an illegal marijuana dispensary in Compton last year.

Investigators never publicly explained all the circumstances surrounding the shooting, but video footage from the shop released by the Los Angeles Sheriff’s Department appears to show Nettles and three co-conspirators entering the dispensary, which was disguised as a smoke shop, and quickly getting into a shootout with a security guard.

Wilson High School senior Justin Culberson, who was participating in the robbery, was killed in the exchange, according to authorities.

Nettles fled the scene but was eventually taken into custody and charged with murder and attempted murder, according to authorities. Nettles pleaded not guilty and remained jailed in lieu of over $3 million in bail.

On May 13, the 19-year-old had been watching TV in another inmate’s cell around 1:30 a.m. and going through photos when he decided to go back to his own cell, deputies said, according to the medical examiner’s report.

Thirty minutes later, a deputy responsible for checking on the inmates found Nettles lying prone on the bottom bunk of a cell, deputies said in a statement, according to the medical examiner report.

“The decedent was found to be unresponsive with blood and foam coming from his mouth and nostrils” deputies said in the statement.

Despite deputies attempting to reverse the effects of the drugs by administering Narcan and efforts to resuscitate him, Nettles was pronounced dead just before 3 a.m.

During an autopsy, the medical examiner’s office found traces of fentanyl in his blood and ruled he had accidentally died from its effects, according to the report.

Deputies did not say in their statement to the medical examiner’s office where Nettles could have gotten drugs, though many inmates get drugs delivered into the facility through the mail, according to Sheriff Robert Luna.

Nettles was the 15th person to die in Los Angeles County Jail this year. Since his death, 29 more inmates have died. Of those 29, at least 3 died from the effects of drugs, according to the department’s records.

A month after his death, Nettles’ mother appeared in front of the Los Angeles Board of Supervisors and participated in a rally demanding Men’s Central Jail be closed, according to the Los Angeles Times.

“I don’t know what it’s going to take for you guys to close that jail,” she said to the board, wearing a shirt with her son’s face on it. “How many people actually have to die?”

In a recent interview with the Los Angeles Times, Luna said he’s been developing a plan to drastically change Men’s Central Jail — and possibly close it altogether.

“Men’s Central Jail needs to be replaced,” he said in the interview. “We need something that resembles a care campus that can deal with what custody should look like toward the future.”

According to Luna, that could include eliminating the mail system to stop drugs from getting into the jails, and instead allowing tablets inside so that inmates can continue communicating with their families.