Documentary Alleges Diddy Took Out Hit on Tupac and Suge Knight, and Knight Retaliated with Hit on Biggie

Using audio-taped interrogations as well as statements from a former investigator, a documentary released on iTunes this week attempts to solve one of hip-hop’s oldest mysteries: Who is responsible for the murders of rappers Tupac Shakur and Christopher "The Notorious B.I.G." Wallace?

The film, entitled Murder Rap, by filmmaker Mike Dorsey, features retired Los Angeles Police Department Detective Greg Kading, who says that media mogul Sean "Diddy" Combs, one of Biggie Small's closest confidants, took out a hit on Tupac Shakur and his manager, Marion Hugh "Suge" Knight. In retaliation, Kading alleges, Knight paid somebody to kill Wallace.

However, a source close to Combs claims Kading's accusations are baseless.

Kading also insists the murders were solved long ago by the Los Angeles Police Department.

Kading alleges that detectives learned Combs had allegedly hired a Crips gang member named Duane Keith "Keffe D" Davis to kill Shakur and Knight. Combs allegedly agreed to pay Davis $1 million for the hit, Kading says.

On the night of Sept. 7, 1996, Kading claims Keffe D's nephew, Orlando "Baby Lane" Anderson, gunned down Shakur in Las Vegas; Knight survived the attack.

According to Kading, Knight subsequently hired Bloods gang member Wardell "Poochie" Fouse to kill Biggie in retaliation for $13,000. Biggie was murdered on March 9, 1997, in Los Angeles.

Detective: Combs Wasn't Charged Because He Was a Celebrity

As he does in the film, Kading alleges in an interview with PEOPLE that Los Angeles authorities decided not to charge Combs partly because of his celebrity. They also declined to pursue the case more than five years ago because both of the suspected gunmen were dead, having died in unrelated incidents.

"Suge Knight hired someone to shoot Smalls because he'd heard Biggie was in Las Vegas and provided the gun to the Crips, which was erroneous information," Kading tells PEOPLE.

Kading believes that prior to the murders, Combs was under the impression that Suge Knight was trying to have him killed because Knight believed Combs had something to do with the murder of one of Knight's friends.

"[Combs] was in a precarious situation. He knew he was being hunted down in Los Angeles and he knew Suge held him responsible for the murder of one of his friends. At that point, Suge had already accosted a producer to find out where Combs' house in Los Angeles was."

Combs, according to Kading, "was in a state of desperation and knew that if he didn't take matters into his own hands, he might have been the one murdered. It was a preemptive strike."

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The L.A. Times Retracted a Story Fingering Combs in 2008

A number of music industry and hip-hop insiders confirm to PEOPLE that rumors of Combs' alleged involvement in the killings have swirled for years. But in the same breath, these same insiders were quick to point out the existence of other rumors, which all finger other potential suspects.

A spokesperson for the Los Angeles Police Department tells PEOPLE that agency will not be issuing any comments on the contents of Murder Rap. The detectives assigned to Biggie's homicide case were not available for interviews.

Davis' lawyer, Edi M.O. Faal, could not be reached for comment. Anderson and Fouse are both deceased.

Knight is currently in jail awaiting trial and his attorney, Stephen Schwartz, did not respond to calls Thursday seeking comment.

Representatives for Combs did not respond to PEOPLE's requests for an interview to address Kading's allegations.

A source familiar with the allegations tells PEOPLE: "There is no truth to this – it's an old story and every few years, this kicks itself up. The LA Times ran a story in 2008 and they had to retract it because there is no truth to it."

Indeed, the Los Angeles Times did retract a piece seven years ago that alleged Combs had "orchestrated an attack in which Shakur was injured at the Quad Recording Studios in New York on Nov. 30, 1994." The article suggested Combs wanted to punish the rapper for refusing to sign with his label.

The Times investigated the piece's accuracy after it was questioned days after appearing in print, and pulled from its website because the story was based on claims the paper "no longer believes to be credible."

Kading: 'Within Law Enforcement, We Know What Took Place'

Kading insists in an interview with PEOPLE that detectives have not worked on either murder case since 2010, when he decided to retire from the force.

"Within law enforcement, we know what took place and we've corroborated claims from the various players who were involved," Kading tells PEOPLE.

"Both cases have been resolved on an investigative level, so there's no more work being done on these cases. They remain open cold case homicides because no one was ever prosecuted."

Kading says that he wrote his 2011 book about his claims because he needed to "set the record straight so there could be an accurate accounting" of what happened.

"Fans don't have to accept that there's no answers in these cases," Kading says. "They can have answers. I felt I had an obligation to provide this information to the public."

• With reporting by LIZ McNEIL