Wallace's murder remains unsolved and there are many theories regarding the identities and motives of the murderers. Immediately after the shooting, reports surfaced linking the Shakur and Wallace murders, because of the similarities in the drive-by shootings. In 1997, Los Angeles Times authors Chuck Philips and Matt Laitt reported that the key suspect was a member of the Crips acting in service of a personal financial motive.

A 2002 book by Randall Sullivan called Labyrinth compiled information about the murders of Wallace and Shakur based on information provided by retired LAPD detective Russell Poole. In the book, Sullivan accused Marion "Suge" Knight, co-founder of Death Row Records and a known Bloods affiliate, of conspiring with David Mack, an LAPD officer (whom Sullivan alleged without evidence to be a Death Row employee), to kill Wallace and make Shakur's and Wallace's death appear the result of a bi-coastal rap rivalry. The book stated that one of Mack's alleged associates, Amir Muhammad (although there was never evidence that Muhammad knew Mack), was the hitman. The theory was based on evidence provided by an informant (who later recanted), and an alleged but unsupported resemblance of Muhammed to the facial composite. Filmmaker Nick Broomfield released a documentary, Biggie & Tupac, based on information from the book.

Broomfield's low-budget documentary on the deaths of Tupac and Biggie was as the New York Times described it, a "largely speculative" and "circumstantial" account relying on flimsy evidence, failing to "present counter-evidence" or "question sources." Moreover, the motive suggested for the murder of Biggie in the Broomfield film—to decrease suspicion for the Shakur shooting six months earlier—was, as The New York Times put it, "unsupported in the film."

An article published in Rolling Stone by Sullivan in December 2005 accused the LAPD of not fully investigating links with Death Row Records based on Poole's evidence. Sullivan claimed that Sean Combs "failed to fully cooperate with the investigation" and according to Poole, encouraged Bad Boy staff to do the same. The accuracy of the article was later refuted in a letter by the Assistant Managing Editor of the LA Times accusing Sullivan of using "shoddy tactics." Sullivan, in response, quoted the lead attorney of the Wallace estate calling the newspaper "a co-conspirator in the cover-up." In alluding to Randall Sullivan-Russell Poole theory that formed the basis of the Wallace family's dismissed 500 million dollar suit against the City of Los Angeles, The New York Times wrote: "A cottage industry of criminal speculation has sprung up around the case, with documentaries, books and a stream of lurid magazine articles implicating gangs, crooked cops and a cross-country rap rivalry," noting that everything associated with the death of the Notorious BIG had been "big business."

Retired LAPD detective Greg Kading, who worked on the Biggie Smalls murder case for three years, alleges that the rapper was shot by Wardell Fouse (a.k.a Darnell Bolton and "Poochie"), an associate of Suge Knight, who was later killed in July 2003 after being shot in the back while riding his motorcycle. Kading believes Knight hired Poochie via his girlfriend "Theresa Swann" to kill Biggie to avenge the death of Tupac, whom Kading alleges was killed under the orders of Sean Combs.