STATELINE, Nev. — Law enforcement officials in Nevada and South Lake Tahoe expanded their search Thursday for a missing Petaluma woman, combing the snowy region by air and land, conducting a room-to-room sweep of her hotel and poring over her cellphone activity.
But so far, there has been no sign of Alyssa Byrne, 19, who vanished New Year's Eve while attending a three-day music festival at Lake Tahoe Community College.
The aerial search will resume this morning with help from an additional helicopter from Reno, Douglas County Undersheriff Paul Howell said in a news conference.
He stressed the importance of finding Byrne soon because of the below-freezing overnight temperatures in the ski resort area.
"We're concerned," he said. "And we're putting every resource we have into it."
Howell said the last activity from Byrne's cellphone was recorded at 12:03 a.m. Jan. 1, or about 10 minutes later than previously thought.
Detectives were unable to say if it was a call or text message, he said.
"Since that time, the phone has gone inactive," Howell said.
He cautioned that activity on her phone wouldn't necessarily pinpoint her location — just her phone's.
The Rescue Coordination Center at Tyndall Air Force Base in Florida is examining the cell activity, Howell said.
The FBI and search and rescue officials from Nevada and California also joined the search, as have those from the National Center for Missing and Exploited Children.
Howell said authorities were doing a "room-to-room search" of the Horizon Casino Resort in Stateline, where Byrne and her friends were staying.
Security officers at the Horizon and other casinos are going through their security footage, Howell said.
Friends and family blanketed the South Lake Tahoe area with fliers describing the missing woman and urging anyone with information to call authorities.
Her father, Kevin Byrne, drove to Stateline on Wednesday to help find his daughter. He said Thursday he was optimistic since police "didn't find her body in the snow."
"When this is all said and done and we get her back home, then we'll have a nice party," he said Thursday night while seated near the Horizon resort lobby.
However, he expressed concern that the 2011 Casa Grande High School graduate didn't return repeated calls to her cell. And he said he regretted not checking out the music festival more closely. He feared it was a "rave" — a type of music event characterized by drug use.
"Maybe she partied harder than normal," he said. "I don't know."
Concerns for Byrne's safety were mounting Thursday amid a sense that something wasn't right with her in the hours before she disappeared.
Friends who saw her shortly before she went missing said she wasn't acting quite herself when she unexpectedly left a New Year's Eve concert an hour before midnight and, later, passed on a chance to visit with old high school friends at her hotel in the wee hours of New Year's Day.