The FBI has joined the investigation into what police now say was likely the abduction of a teenage woman from a friend's Reno, Nev., home sometime Sunday morning.
Brianna Denison, 19, was reported missing when a friend she was staying with after attending a party at a Reno casino awoke Sunday to find Denison missing and a small blood stain on the pillow she had been given to use.
"We are investigating this as an abduction," Steve Frady, a spokesman for the Reno Police Department, confirmed to ABC News.
The blood stain, which is being analyzed in a crime lab, was not the only factor that caused alarm for authorities and family members of Denison, who is a native of Reno. Dension left the house without her shoes, cell phone or purse. Authorities believe she was barefoot, wearing only what she had worn to bed -- sweats and a white tank top.
As officers and canines canvassed the area near the house today for any sign of Denison, the young woman's family offered an unspecified reward in the case, as did the Secret Witness Program, an anonymous tip line taking information on her disappearance.
Tips, Frady said, continue to come to investigators. "We are continuing to talk to people," he said. "We are getting information, and we're continuing to follow those leads."
Authorities also continue to seek an unnamed man in his 40s, who they believe may have information about Denison's whereabouts.
The man became implicated in the abduction investigation after he dropped another one of Denison's friends at the same house where she had been staying. Many college-age women share the rental house near the University of Nevada.
Authorities say that the man picked up Denison's friend around 1 a.m. Sunday at the Sands Regency Hotel Casino after she failed to find a taxi. The driver, considered for now a "person of interest" rather than a "suspect," dropped the young woman at the house roughly three hours before Denison and another friend returned from the same party.
Denison was at home for winter break from Santa Barbara City College in California. She and her friends were attending events tied to the Summer Winter Action Tours Martin Luther King Jr. weekend. It's an annual party, with events in Reno and Lake Tahoe, that Denison reportedly had attended in the past.
Reno police released a surveillance image showing the man's beige or light-brown Chevrolet Suburban leaving the casino's parking lot Sunday morning. The unidentified driver is described as a white male, possibly of Latin descent, with a medium build. He was well-dressed, according to police.
"It's all very suspicious at this point," Reno police Lt. Robert Macdonald told ABC News Monday. "She hasn't attempted contact with any family members or friends." Denison's mother, her only surviving parent, has been in contact with authorities and her boyfriend, who lives in Oregon, was in his home state Saturday night, authorities there confirmed to Reno police.
Authorities also announced Monday that a brown stuffed bear about 2 feet tall was missing from the house where the man had dropped Denison's friend. Denison's friend gave her the stuffed animal to use as an additional pillow before the two went to bed around 4 a.m. Sunday. Denison was reported missing around 10:30 a.m. Sunday.
Reno police said that there was no initial indication that Denison had been drinking heavily or using drugs Saturday night, and that none of the roommates who live in the house reported any altercations at the casino party. The house was not locked during the night, so there is no evidence of a forced entry.
Reno police also urged caution regarding two reports about Denison's disappearance -- one about text messages that may have indicated a breakup between Denison and her boyfriend and the other about possible connections between Denison's disappearance and two unsolved assaults of young women near the university.
"There was some texting going on back and forth, but I don't have any more information than that," Frady said.
As for a link between Denison's disappearance and the pair of assaults, police said in a statement that "there does not appear to be a connection," and that the two assaults remain under investigation.
Denison is described as 5 feet tall, weighing 98 pounds, with long dark brown hair and blue eyes. Detectives say Denison may be wearing light-blue or pink sweat pants and a white tank top.