Paul Huebl has alleged that the iconic singer was killed by two men who came to collect a debt, and claimed that the culprits have also been caught on video, reports National Enquirer.
Huebl said: "I have evidence that points to Whitney being a victim of high-powered drug dealers who sent thugs to collect a huge debt she owed for drugs."
He suggested that two unknown men repeatedly arrived at the Beverly Hilton, where Houston was staying when she was discovered dead in the bath.
He has reportedly collected evidence from drug informants and revisited the coroner's report.
The PI, who hopes that viewing the new information will reveal the "truth", is now handing over his findings to the FBI.
The coroner recorded that 'no foul play' was involved in Houston's death. However, Huebl strongly disagreed, saying: "Whitney's body shows classic defence wounds that would have occurred while she was battling for her life."
Houston's drugs debt was reportedly in excess of $1.5 million (£930,000).
Photo gallery - Whitney Houston: