By Lacey Johnson

FAIRFAX, Va. (Reuters) - The accuser in a Virginia sexual assault case involving a man also charged in the high-profile murder of a college student testified on Monday that he grabbed her near her door and choked her until she was unconscious.

On the first day of the trial of Jesse Matthew Jr., 33, of Charlottesville, the alleged victim told jurors that she was returning from grocery shopping in September 2005 when Matthew grabbed her and pulled her out of sight.

"I was just three or four steps from my door," said the woman, who wept during part of her testimony. "He sealed my nose and my mouth with his hands and he choked me" until she became unconscious.

Commonwealth's Attorney Raymond Morrogh told jurors during opening arguments in Fairfax County Circuit Court that the woman was unmarried and a 26-year-old virgin when the alleged attack took place in Fairfax, a Washington suburb.

Skin cells gathered from beneath the woman's fingernails following the assault were tested against Matthew's and the DNA was a match, said Morrogh.

But defense attorney Robert Frank argued that the DNA match "came from an innocent contact." Reuters' policy is not to name the victims of sex crimes.

Matthew also is charged with abducting and killing Hannah Graham, a University of Virginia sophomore, last year in a case that drew national attention.

Albemarle County prosecutors charged him with capital murder in May, making him eligible for the death penalty if convicted in that case.

The sexual assault trial is scheduled to last two weeks. Matthew is charged with attempted capital murder during abduction, abduction with intent to defile, and sexual penetration with an object.

Virginia State Police have said forensic evidence links Matthew to the disappearance of a Virginia Tech student in October 2009. Her body was discovered in 2010.

(Reporting by Lacey Johnson; Editing by Ian Simpson and Eric Beech)