Robert De Niro's Grandson's Death: Teen's Suspected Drug Dealer Known as 'the Percocet Princess' Arrested by NYPD

A woman known as the "Percocet Princess" has been arrested in connection to the suspected overdose death of Robert De Niro's grandson Leandro.

On Thursday, July 13 — less than two weeks after the 19-year-old's passing — Sofia Haley Marks, 20, was found by the NYPD amid a city-wide drug investigation.

Marks, who is believed to have sold the teenager fentanyl-laced pills, is expected to be arraigned in federal court on Friday.

An official cause of death has yet to be determined, but Leandro's mother, Drena De Niro, confirmed on social media that drugs were to blame.

"Someone sold him fentanyl-laced pills that they knew were laced yet still sold them to him," she said. "So for all these people still f****** around selling and buying this s***, my son is gone forever."

Leandro's body was found on July 1 in a Manhattan apartment with a powdery substance and drug paraphernalia nearby.

Drena, 51, was the one to first announce her child's tragic passing.

"My beautiful sweet angel. I have loved you beyond words or description from the moment I felt you in my belly. You have been my joy, my heart and all that was ever pure and real in my life. I wish I was with you right now. I wish I was with you," the actress wrote. "I don’t know how to live without you, but I’ll try to go on and spread the love and light that you so made me feel in getting to be your mama."

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"You were so deeply loved and appreciated and I wish that love alone could have saved you 😞. I’m so sorry my baby. I’m so sorry @carlosmare 😢💔. Rest in Peace and Eternal Paradise my darling boy 🙏🏽💔💔💔💔💔🕊️🕊️🕊️🕊️," Drena concluded, tagging Leandro's father, Carlos Rodriguez.

The iconic actor, 79, released a message of his own.

"I’m deeply distressed by the passing of my beloved grandson Leo," he stated. "We’re greatly appreciative of the condolences from everyone. We ask that we please be given privacy to grieve our loss of Leo."

A funeral for Leandro was held on Saturday, July 8, in New York City.