Robert De Niro's daughter says her son, Leandro, died from fentanyl-laced pills

• Robert De Niro's grandson Leandro De Niro Rodriguez was found dead in New York City on Sunday.
• In a new Instagram post, his mother, Drena De Niro, said Leandro "didn't deserve to die like this."

Robert De Niro's elder daughter says her 19-year-old son, Leandro De Niro Rodriguez, who was found dead on Sunday, "didn't deserve to die like this."

In an Instagram post, Drena De Niro said her son's death was drug related.

"Someone sold him fentanyl-laced pills that they knew were laced yet still sold them to him," she wrote on Instagram. "So for all these people still fucking around selling and buying this shit, my son is gone forever."

Leandro was the son of De Niro's eldest daughter and the artist Carlos Rodriguez.

On Tuesday, days after the teen was found dead at an iconic lower Manhattan building, Drena posted a black-and-white photo of her son on Instagram.

In the post, she began by expressing her gratitude to her followers for "all the love, the messages, calls, texts, emails, the friends and family that held me up these last 24 hrs."

"None of this is right or fair and my heart hurts in a way I never knew possible while still breathing and barely functioning. Leo my darling I love you today like the first day I held you in my arms," Drena wrote.

Drena added that "the same man that picked us up from the hospital when you were born drove us to the funeral home where I touched and held you for the last time."

Her post continued: "You didn't deserve to die like this but I can only believe that God needed a strong powerful angel in their army. I'm holding you every second of every moment I'm my heart and memories until I'm with you again."

The Office of the Chief Medical Examiner has yet to determine Leandro's cause of death.

A spokesperson for the New York Police Department told Insider that officers found a male unconscious and unresponsive when responding to a 911 call at 55 Wall Street just before 2:30 p.m. on Sunday.

The 19-year-old teen was later identified as Leandro and pronounced dead by EMS on the scene, according to the NYPD.

The building he was found in, Cipriani Wall Street, houses luxe apartments, hotel rooms, and an exclusive old-money-inspired social club.

Raphael De Niro, Leandro's uncle who is also De Niro's eldest son, is a real-estate broker who previously sold apartments at Cipriani Wall Street, The Real Deal reported in 2009.

The "Raging Bull" actor, who adopted Drena in 1976 during his first marriage to Diahnne Abbott, said in a statement to People on Monday that he was "deeply distressed" by the death of his grandson and asked that his family be given privacy to "grieve our loss of Leo."

Before his death, Leandro followed in his grandfather's footsteps as an actor. He had credits in the films "Cabaret Maxime," "The Collection," and "A Star Is Born," the last of which he appeared in alongside his mother.