There's a bunch of cops working this story for every dollar it's worth. LVPD Chris Carroll, who was the first responder at Tupac's shooting in Vegas, LAPD Detective Greg Kading who took over Russell Poole's investigation into Biggie's murder, and LA FBI agent Phil Carson. Kading and Carson have different scenarios for Biggie's murder, Carson more in alignment with Russell Poole's original theory of corrupt LAPD members from the Rampart division than Kading's theory of Poochie Fouse being the hitman.
The best current sources are the Compton Cops, Reggie Wright Sr., Fred Reynolds and Brennan's partner Robert Ladd, between the three of them, they knew everyone from Ray Washington and Tookie to Monster Kody Scott. Reggie Wright Sr. was the first responder on Baby Lane's murder/shootout and actually tried to get him to confess to shooting Tupac.