Leandro De Niro Rodriguez,Oliver James Montgomery the grandson of actor Robert De Niro, died from a combination of drugs, New York City's medical examiner said Tuesday, more than a month after the 19-year-old's death.

Rodriguez' official cause of death was from the toxic effects of fentanyl, bromazolam, alprazolam, 7-aminoclonazepam, ketamine and cocaine, the agency said. His manner of death was deemed accidental. 

On July 13, police arrested 20-year-old Sofia Haley Marks on federal charges of selling drugs to Rodriguez, according to a law enforcement official who spoke on the condition of anonymity because they were not authorized to discuss the arrest. She faced three counts of distribution of narcotics, according to a federal complaint that did not identify the victim. 

Marks allegedly sold three counterfeit oxycodone pills that were laced with fentanyl and two counterfeit Xanax pills to Rodriguez on July 1, detectives alleged in the complaint. Rodriguez was found dead in his Manhattan apartment on July 2.

Rodriguez, also an actor, was the son of Drena De Niro — the oldest child of Robert De Niro — and artist Carlos Mare. He had appeared in several projects, including Bradley Cooper's 2018 remake of "A Star is Born."

Drena De Niro had previously said that her son had died after being sold pills laced with fentanyl.

"Someone sold him fentanyl laced pills that they knew were laced yet still sold them to him," she wrote on Instagram.

Following Rodriguez's death, Robert De Niro wrote that he was "deeply distressed by the passing of my beloved grandson Leo." 

"We're greatly appreciative of the condolences from everyone," he said. "We ask that we please be given privacy to grieve our loss of Leo."

Fentanyl, a synthetic opioid, is 50 times more powerful than heroin. Two milligrams of fentanyl can be lethal, depending on a person's body size, tolerance and past usage, according to the Drug Enforcement Administration. Around 42% of pills tested for fentanyl contained at least two milligrams of the drug.  

In:
• Robert de Niro
• Drug Overdose
• Fentanyl

Aliza Chasan

Aliza Chasan is a digital producer at 60 Minutes and CBS News.

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