The detective claimed he was forced out of the LAPD after uncovering police connections to the rapper’s murder.

Russell Poole, the detective known for his dedicated investigation into the 1997 murder of Biggie Smalls, died today, NBC reports.

Poole left the LAPD in 1999, and he has said that his departure was due to his investigation suggesting that police were complicit in the rapper’s murder. He later wrote a book about the events, generously titled LAbyrinth: A Detective Investigates the Murders of Tupac Shakur and Notorious B.I.G., the Implication of Death Row Records’ Suge Knight, and the Origins of the Los Angeles Police Scandal.

Knight is currently in jail awaiting a possible murder trial in a separate incident from this year, and was never implicated in Wallace’s killing.

Poole reportedly died suddenly, possibly of a heart attack, while speaking with homicide detectives about a case.