Bill Cosby -- Accuser Chloe Goins is a LIAR ... I Wasn't Even There

Bill Cosby has PROOF he was not even at the Playboy Mansion the night one of his accusers claims he sexually assaulted her ... so says Cosby's lawyer.

Legal pit bull Marty Singer tells TMZ ... on the date in question -- August 9, 2008 -- he has flight and telephone records that clearly place Cosby in New York City ... 2,500 miles from the Mansion.

Chloe Goins claims Cosby gave her a drink at the Mansion during the Midsummer Night's Party and the next thing she knew she was naked in a bedroom as Cosby sucked her toes and masturbated.

Goins filed a police report this week with the LAPD, but it's problematic. The alleged incident occurred a little more than 6 years ago, and the statute of limitations is 6 years for all sexual assaults except rape -- the rape statute is 10 years, but up to this point Goins never alleged penetration.

Singer says Cosby's team will be "providing documentary evidence to the appropriate authorities which conclusively establishes Mr. Cosby's whereabouts on August 9th."

And one more thing ... the August 9th party was extensively covered by the media, and photos were published of the various celebs in attendance, including Paris Hilton, Matthew Perry, Jim Belushi, Jason Statham and Bill Maher. There are no pics or mention of Cosby.