(CNN) -- Murder charges were filed Tuesday against a man accused of killing the pregnant wife of a Marine in California.
Erin Corwin, 19 and three months pregnant, had been missing since June 28 after she said she was going to Joshua Tree National Park to scout trails. Over the weekend, searchers found her body about 140 feet down a mine shaft.
Her former neighbor, Christopher Lee, 24, was arrested Sunday in Alaska. He is awaiting extradition to California.
He faces a murder charge and the special circumstance allegation of "lying in wait," which means he could face life in prison without parole or death, if found guilty, according to San Bernardino County District Attorney Michael Ramos.
"The decision regarding which penalty will be sought will be made after a full review of the facts and evidence in the case," he said.
Lee had been a suspect from the beginning.
Corwin didn't go to Joshua Tree National Park on the day she disappeared, police said in a statement of probable cause written in July. Instead her car was found a few miles from where she lived next door to Lee and his wife, Nicole.
Detectives found footprints next to Corwin's abandoned car that led to tire tracks. Investigators said those tire tracks were the same width and same width apart as the tires on Lee's Jeep.
According to the court document, several people, including a friend of Erin Corwin's in Tennessee, told investigators that Corwin and Lee were having an affair. He admitted to kissing her but told detectives the two had never had sexual intercourse.
Lee also told police that on the day Corwin disappeared he had gone hunting.
More than 100 mine shafts were searched before a sheriff's team found Corwin's body. Authorities used cell phone information to narrow the search area to 300 square miles.
The area included remote land belonging to the federal government's Bureau of Land Management.