Richmond police are pursuing a theory that Taylor Marie Behl voluntarily left Virginia Commonwealth University on Sept. 5 and that the missing freshman was not abducted, officials said yesterday.

"If she's hearing any of this, we want her to call in," said Cynthia Price, a police spokeswoman. "We want her to know that she shouldn't worry that it's gotten so much attention. We just want her to let us know that she's safe."

Although there is no evidence that Behl, 17, is in any danger, police remain "very concerned about her safety," Price said. An Amber Alert was issued for Behl after 11 p.m. Thursday by the Virginia State Police and deactivated at noon yesterday. Most alerts are posted for about 12 hours, Price said. She said it was issued for three reasons: Behl is a juvenile; she and her car have not been found in more than a week; and no solid tips about her whereabouts have surfaced.

Police have said consistently that they do not suspect foul play. However, on Thursday, police upgraded the case from a search for a missing person to a full-fledged criminal investigation, not because there was evidence that a crime had occurred but because it allows them to employ various resources, including search warrants and the Amber Alert.

When an Amber Alert is issued, information about missing and abducted children is disseminated immediately through the media and on highway signs. No alert was called for when she was reported missing because the case did not meet the criteria, Price said.

Several tips were received yesterday, Price said, and a task force that includes about a dozen investigators from Richmond police, VCU police, Virginia State Police and the state's attorney's general was pursuing them.

Among the theories about Behl's disappearance is that she crashed her 1997 Ford Escort in an area that has not been searched. Authorities are again interviewing her friends and acquaintances, including people she might have met online at Web sites she maintained.

A profile Behl posted on remains active, although she has not logged on since Sept. 4, the day before she disappeared. And a Web log she kept at has not been updated since April, although people left messages begging for her safe return as recently as yesterday.

Behl, a June graduate of Madison High School in Vienna, was last seen about 10 p.m. Sept. 5 after a late dinner at a cafe. She found her roommate in their dorm room with a boyfriend and told her that she would leave for a while to give them privacy, police said.

Police said she was wearing jeans and a hooded black sweat shirt and took only her car keys and a credit card. Behl's mother said her daughter did not take her credit card with her and had about $40 in cash.

Behl continues to receive e-mails but has not logged on to read them, police said. Her credit card has not been used, and the last call made on her cell phone was at 9:44 p.m. the night she disappeared.

Police said dozens of tips generated in the past week have failed to provide credible information on Behl's whereabouts or the location of her car.

College freshman Taylor Marie Behl disappeared Sept. 5.