The 24-year-old former neighbor and suspected lover of a U.S. Marine’s pregnant wife who had been found dead at the bottom of a mine shaft was charged Tuesday with murder.

Christopher Brandon Lee was due in court later Tuesday in Alaska, where he was arrested Sunday on suspicion of murder in the death of 19-year-old Erin Corwin, whose husband was stationed in Twentynine Palms.

Corwin, who was three months pregnant when she was reported missing June 28, was found dead Saturday after hundreds of volunteers and search-and-rescue experts searched a 300 square-mile desert area for her.

The San Bernardino County Sheriff’s Department announced Lee’s arrest and details about where Corwin’s body was found at a news conference Monday.

Lee allegedly killed Corwin on or about June 28 “with malice aforethought,” according to a criminal complaint filed against him.

Detectives believed Lee had an affair with Corwin, according to court documents.

Lee was charged with murder with the special circumstance allegation of “lying in wait,” increasing the potential sentence to life without parole or death, according to the San Bernardino County District Attorney’s Office.

Lee was awaiting extradition to California; he was set to face a judge for his first hearing in Alaska.

Detectives believe that Corwin got into Lee’s Jeep before she disappeared. Her body was discovered at the bottom of a 140-foot mine shaft in a remote area on federal land outside of Joshua Tree National Park.

Lee’s wife told the owner of a horse ranch where Corwin volunteered that “detectives did not have a case against them” and that Corwin’s body would never be found, according to an investigator’s affidavit.

Additional arrests in the case were possible, authorities said Monday.