A soldier at Joint Base Lewis-McChord is accused of shooting and killing his pregnant wife and another soldier, then leading police on a high-speed chase that ended with his capture by a SWAT squad in a vast wildlife refuge near the military base.

Spc. John Robert Maupin, 21, was arrested at about 1 a.m. Friday for the killings four hours earlier of his 24-year-old wife, Julia Maupin, and Sgt. Brandon Rudlaff, 26, who family members described as Julia Maupin’s boyfriend, according to local authorities.

John Maupin and Brandon Rudlaff were assigned to the 7th Infantry Division at Lewis-McChord, base officials said.

John Maupin, his wife, and Rudlaff lived together in a house in Lacey, a town south of the joint Army-Air Force base near Tacoma, according to a court affidavit filed in Washington Superior Court on Friday by the Thurston County Prosecutor’s Office. Julia Maupin’s mother, Colleen O’Toole, and her partner, Michael Delgado, also lived in the house.

Lacey Police responded Thursday to a 911 call at about 9:05 p.m. from the house where they all lived. O’Toole and Delgado directed police upstairs where they found Rudlaff lying in the hallway and Julia Maupin on the floor of a bedroom. Both had been shot.

The Lacey Fire Department also responded to the scene and confirmed both were dead.

“Brandon and Julia both had trauma to their heads that appeared consistent with gunshot wounds,” according to the affidavit.

O’Toole told police that Julia was eight months pregnant. The unborn baby did not survive, authorities said.

O’Toole also told police that John and Julia Maupin frequently argued, and John Maupin had threatened suicide several times in the past.

Thursday’s incident also began with an argument over John Maupin’s use of his wife’s phone, with gunshots heard in the bedroom shared by Julia Maupin and Brandon Rudlaff, according to the affidavit.

John Maupin then went downstairs, where Delgado was watching television. Delgado told police that Maupin had a handgun and told him to back away. Maupin went out the door, got into a white 2020 Hyundai Sonata and sped away.

O’Toole said she then called 911, while Delgado went to a neighbor’s also to call local authorities.

A police officer in Olympia spotted John Maupin’s car traveling north on Interstate 5 at about 9:15 p.m. and attempted to stop his car.

Maupin instead initiated a high-speed car chase of more than 110 mph. Other police joined the pursuit. As the sun was setting, Maupin drove into the Billy Frank Jr. Nisqually National Wildlife Refuge. He abandoned his car and tried to hide in the wetlands.

A Washington State Patrol helicopter and a Thurston County SWAT squad were dispatched to search for Maupin. He was captured at about 1 a.m. Friday in a swampy area.

Maupin told Lacey police that an “alter ego” named “New John” had taken over his consciousness and he recalled nothing of the shootings or his attempt to flee. Police found a handgun in the glove compartment of the car that Maupin was driving.

County prosecutors wrote in the affidavit that they will seek two counts of second-degree murder, a count of second-degree domestic violence assault, and one count of eluding police against Maupin.

Maupin was being held in the Thurston County Corrections Facility in Olympia.

An exit sign for Joint Base Lewis-McChord on Interstate 5 near Tacoma, Wash. (Gary Warner/Stars and Stripes)