Cpl. Christopher Lee and his wife, Nichole, lived next door to Corwin and her husband, Jonathan, also a Marine corporal, at the Marine Corps Air Ground Combat Center in Twentynine Palms, Calif. Lee left the Marines shortly after Corwin disappeared in late June and returned to Alaska, his home state.
Corwin's body was found Saturday in a deep High Desert mineshaft. Lee was arrested Sunday evening in Anchorage.
"The San Bernardino County Sheriff's Department confirmed to us early Monday, August 18th that Erin's body has been found," Corwin's family said in a statement. "While we were praying for a different outcome, we cannot begin to express the gratitude we have for every person that has been involved in the search for Erin."
The Desert Sun said that documents show investigators believe Corwin and Lee were having an affair. Corwin was three months pregnant when she vanished.
Jonathan Corwin said his wife had told him she planned to visit Joshua Tree National Park.
Corwin's car was discovered after she disappeared with a set of shoe prints leading to another vehicle. That had tire tracks matching Lee's Jeep Cherokee, investigators said.