DEKALB, Ill. (CBS) — Northern Illinois University police confirm that the dorm key of a student who has been missing for six days was found in the woods Tuesday.

Antinette “Toni” Keller, 18, of Plainfield, left her dorm for a walk on Thursday of last week, and has not been seen since.

She had told friends that she was planning to go for a walk near the Junction Center shopping mall on West Lincoln Highway to take photographs.

Keller’s fellow students have been handing out fliers and wearing buttons to spread the word, while police continue to search wooded areas around the campus.

PHOTO GALLERY - CLICK HERE

Toni Keller’s family has been on the campus – as part of the search.

Her father, Roger Keller, told CBS 2’S Mike Parker that living through the hell of the past five days has been “very tough.” He says the family is working hard to give the searchers as many photos and as much information as they can so “they can find her as soon as possible.”

Keller graduated from Neuqua Valley High School in Naperville last spring.

“There is a family out there that doesn’t know what happened to their daughter, doesn’t know where their daughter is or what the outcome will be,” Neuqua Valley principal Bob McBride said.

Keller is a white female, 5 feet 6 inches tall, approximately 130 pounds, with brown hair and blue eyes. She was last seen wearing blue jeans, a gray jacket and a scarf and may have been carrying an art portfolio and professional-grade camera.

Parents and students can keep track of developments on the NIU website, or one of several Facebook sites started by friends.

Anyone who may have seen Keller or having information about her whereabouts should call the NIU Dept. of Public Safety at (815) 753-1212.