Virginia State Police say they believe a Virginia Tech student missing for nearly a month was hitchhiking after she left a Metallica concert.

Police said Friday that witnesses saw a woman fitting the description of 20-year-old Morgan Dana Harrington on a bridge that crosses railroad tracks trying to get a ride.

Harrington became separated from her friends after she left the Charlottesville concert arena Oct. 17 and was denied re-entry. She told them she would find a way home.

SLIDESHOW: Virginia Tech Student Disappears at Concert

Police say they want to hear from anyone who might have loaned a cell phone to a woman fitting Harrington's description.

Police say Harrington was wearing a distinctive necklace made of large crystal chain links.