3:47 PM PT -- Manson's attorney, Howard E. King, tells us, "It is not surprising that the District Attorney, after investigation, summarily rejected the claims made in a police report filed by a former acquaintance against Brian Warner p/k/a Marilyn Manson."

He continues, "The allegations made to the police were and are categorically denied by Mr. Warner and are either completely delusional or part of a calculated attempt to generate publicity for the claimant’s business of selling Manson memorabilia."

"The police report that spurred the investigation was accompanied by the woman’s press release and other attempts to generate publicity that fraudulently claimed she was held captive by Mr. Warner for 48 hours in 2011. Any claim of sexual impropriety or imprisonment at that, or any other, time is false."

Marilyn Manson will not be charged with rape after previously unknown allegations have surfaced.

Legal docs -- obtained by TMZ -- show Manson was recently accused of raping a woman back in October 2011. Exact details of the incident are unclear ... but the Los Angeles County District Attorney's office decided there wasn't enough to charge him, due to "absence of corroboration."

There are also battery and assault with a deadly weapon charges, but those charges won't be filed because the statute of limitations expired. A law enforcement source tells us those charges stem from some sort of cutting that happened during the sex.