Kevin Spacey may be charged with sexual assault in California, in the first known investigation outside of the UK.
There are three active investigations into the actor in London, but prosecutors in Los Angeles may also be prepared to press charges.
Spacey is alleged to have attacked a man in West Hollywood in October 1992.
Prosecutors from LA District Attorney's industry sex crimes task force may bring a sexual assault charge after being handed details by police.
An LA county sheriff spokesman Nicole Nishida said the force's "special victims bureau began an investigation into allegations of a sexual assault involving Mr Kevin Spacey on December 11, 2017".
"The events were reported to have taken place in October of 1992 in West Hollywood involving a male adult," she added.
Prosecutors started reviewing the case from 5 April.
Metropolitan Police are investigating allegations of sexual assault against the Oscar-winning actor, spanning from 2005 to 2008.
Anthony Rapp said he was 14 when Spacey, then 26, made a sexual advance to him in 1986.
Spacey said he did not remember the encounter and apologised for "inappropriate drunken behaviour".
After his allegation became public, 20 people from the Old Vic theatre in London also came forward with allegations of misconduct when he had been the artistic director between 2004 and 2015.
More from Kevin Spacey
He was sacked from Netflix's House of Cards and erased from the film All The Money In The World, with the reshoots costing millions of dollars.
A spokesman for Spacey did not comment on the US investigation.
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