UPDATE: Fifteen-Year-Old Girl Missing, Believed to be With Man Wanted on $1.8 Million Warrant

Shelby Harris, a 15-year-old student last seen on Halloween wearing a costume, is missing and is believed to be with a man wanted on a felony warrant.

Police released information yesterday, and several media outlets did stories. However, as of 2:30 p.m. Thursday, there were no new leads.

"There's nothing new — we're still following leads but we're coming up against dead ends," said Sgt. Kurt Schlehuber.

"The goal is to keep this information out in the community and maybe get some information that can help bring her home."

Harris told her parents that she would return home at the end of the school day Monday, but never returned, according to Lt. Jeff Bretzing of the .

Harris is white, is 5' 7" tall, about 140 pounds with black hair and brown eyes.  She was last seen wearing a red cape, red shirt, blue jeans, black high heels, and a Mardi Gras mask. 

Police have determined that she is most likely with 25-year-old Gavin McFate, a Livermore resident who is wanted on a $1.8 million warrant in Alameda County for allegedly having sex with a minor.

He is white, 6' 3" and about 210 pounds with brown hair and brown eyes.

Police say it is unknown whether Harris is with McFate voluntarily or against her will.

"We say that because she's 15 and he's 25; we don't have any hard evidence pointing to that," Schlehuber said.

"It's not like an acute abduction where someone kidnapped her and dragged her into a car. But at the same time, we don't really know either way what the specific situation is."

McFate and Harris were last seen in the Concord area on the morning of Nov. 1. They may be driving a late 90s model black Honda Accord or Civic. The car has California license number 4PRM200. 

His profile on MySpace, which didn't look as if it had been updated in recent years, described him as athletic, religious and a professional who works in Dublin.

According to a poster posted by the National Center for Missing and Exploited Children, the two could be headed to the Sacramento area.

Anyone with information should contact the police department at 925-931-5100.