Authorities were asking Metallica fans to check any videos or photos from a concert for any sign of a Virginia Tech student who disappeared sometime during the show, The Roanoke Times reported Wednesday.

Morgan Dana Harrington, 20, has not been seen since she was separated from her friends at the concert at the John Paul Jones Arena in Charlottesville, Va., Saturday night. Police are treating her disappearance as a criminal investigation.

Lt. Joe Rader of the Virginia State Police Department told reporters on Monday that Harrington left her friends at the concert to use the restroom and for some reason wound up outside. It's the arena's policy not to let anyone back in once they've left.

Amy Melvin, her roommate in Blacksburg, Va. told The Roanoke Times Harrington went outside the stadium before Metallica went on stage, but she wasn't sure why.

Rader said that Harrington called her friends to let them know she wouldn't be coming back inside, and vanished sometime after 9:30 p.m. A passerby found her cell phone and purse in a small parking lot near the arena on Sunday morning, Rader said.

"Everyone assumed she'd be coming back," Amanda Melvin, Amy Melvin's older sister, told the newspaper. "Sitting here while Morgan is out there missing isn't a very good feeling,"

An extensive ground search concluded late Wednesday, police said.

Harrington's distraught parents said they talk to her every day and her disappearance is very out of character.

"Morgan is a pretty transparent kid, who's had a really close relationship with us," her father, Dan Harrington, said in a phone interview Tuesday with the Associated Press. "I don't think there are lots of secrets, so this kind of behavior of (her) missing is not something I think we would expect."

Harrington's father, who lives in Roanoke, said his daughter had asked him to help her study for a math test and go through the class schedule for next semester on Sunday. He called her friends around 12:30 p.m. when he realized he had not heard from her.

Dan Harrington told Fox News this not typical behavior for his daughter.

"Morgan is pretty close to us as a family," he said, adidng his daughter didn't have a boyfriend and didn't know if anyone who would want to hurt her. "We don't think she is out there with someone she choose to be with."

Police said Morgan Harrington, a junior majoring in education, was wearing a black T-shirt with "Pantera" across the front in tan letters, a black mini skirt, black tights and black knee-high boots.

She has long blonde hair and blue eyes, is 5-foot-6 and weighs about 120 pounds. She was not carrying an identification card or cell phone.

Anyone with any information about Harrington's disappearance is asked to call the police tipline at (434) 352-3467.

The Associated Press contributed to this report.

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