Lil Peep, Fentanyl-Laced Drugs May Have Played Role in Death

Lil Peep's death investigation has cops now looking to see if the powerful opioid fentanyl played a role in the rapper's death ... TMZ has learned.

Law enforcement sources tell TMZ ... cops in Tucson are on the hunt after receiving multiple tips the New York rapper got his hands on some incredibly toxic drugs laced with the potent opioid.

You'll recall fentanyl also contributed to the accidental ODs of Prince and Eric Chase Bolling Jr.

Cops know fentanyl is a problem in Tucson and beyond. What makes it especially dangerous is that even a tiny dose can kill ... especially someone who is not a regular opioid user.

As we reported ... Lil Peep's body was found on the bus last week with drug paraphernalia, Xanax, loose marijuana and an unknown tan powder.