(Reuters) - Police have found surveillance videos showing a missing University of Virginia student and a witness saw her talking to a man the morning she disappeared, authorities said on Thursday.

Hannah Graham, 18, a sophomore from Alexandria, Virginia, was last heard from in a text message early on Saturday after a night of drinking. Police have deployed bloodhounds and dozens of officers in their search, and the Federal Bureau of Investigation is involved in the case.

Charlottesville police have obtained two videos showing Graham on the city's downtown pedestrian mall early on Saturday, police said in a statement.

They show Graham passing a white man on the street and him following her, police said. The man in the videos went to police late on Wednesday and identified himself.

He said he followed Graham because she appeared to be "somewhat physically distressed" and he wanted to be sure she was safe, the statement said.

The witness said a black man approached Graham and put his arm around her. She stopped and the two began speaking.

"It appeared to the witness that the black male was either known to Ms. Graham or was trying to help her," the statement said.

The witness walked away as the pair talked. The black man is not shown in either video, it said.

Graham's parents, John and Susan Graham, said in a statement on Wednesday that they were devastated. "We fear foul play," they said.

(Reporting by Ian Simpson; Editing by Bill Trott)