(CNN) -- The body of a missing pregnant wife of a Marine based in California was found over the weekend and her former neighbor was arrested in connection with her death, police in San Bernardino County said.
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. On Saturday, searchers found her body about 140 feet down a mine shaft but weren't able to recover and identify it until the next day, San Bernardino County Sheriff John McMahon said.
An autopsy determined Corwin had been killed, the sheriff's department said, without elaborating how she died.
On Sunday night, authorities in Anchorage, Alaska, arrested Christopher Lee, who police say had been having an affair with Corwin.
CNN affiliate KTLA, citing District Attorney Michael Ramos, reported that charges against Lee will be decided in the next two days.
KTLA also reported that it may take four to five weeks before he can be returned to California.
The station said Corwin's husband, Cpl. Jonathan Corwin, hasn't spoken publicly about the case.
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.
San Bernardino County deputies arrested Lee on July 4 for a felony not related to Corwin's disappearance: possession of a destructive device.
KTLA said he posted bail two days later.
More than 100 mine shafts were searched before the 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.
On Saturday, searchers went to the Brooklyn, Los Angeles and Rose of Peru mines. KTLA described the area as remote and off a dirt road accessible by four-wheel drive vehicles.
Searchers located Corwin by using a camera, the sheriff's department said. Because the body was so far from the surface and the air in the mine was poor, it took another day to get to the body and bring it to the surface.