Lawyers for a woman who says President Donald Trump raped her in the 1990s are asking for a sample of his DNA.

The attorneys for advice columnist E. Jean Carroll say they want to determine whether Trump's genetic material is on a dress she says she wore during the encounter. They served a legal notice Thursday to one of Trump's lawyers demanding the sample.

Several other people have already been tested and eliminated as possible contributors to the DNA sample found on the test, according to a lab report obtained by the Associated Press.

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Carroll filed a defamation suit against Trump in November after the president said she was lying about the alleged attack. She accused Trump last summer of raping her in a Bergdorf Goodman dressing room in the '90s. Carroll wrote about the assault in a piece for The New Yorker. Two colleagues later came forward to corroborate her account.

President Trump said in June that Carroll was "totally lying" and that the two had never met. 

“Unidentified male DNA on the dress could prove that Donald Trump not only knows who I am, but also that he violently assaulted me in a dressing room at Bergdorf Goodman and then defamed me by lying about it and impugning my character,” Carroll said in a statement to the Associated Press Thursday. 

Her lawyer, Kaplan, said it was “standard operating procedure” in a sexual assault investigation to request a DNA sample from the accused.

“As a result, we’ve requested a simple saliva sample from Mr. Trump to test his DNA, and there really is no valid basis for him to object,” she said.

The Associated Press sent a message to Trump's attorney seeking comment.