New information shows a Marine staff sergeant found dead in a burning home near Richlands, North Carolina, was killed in an act of self-defense by his estranged wife after he killed her boyfriend, officials with the Onslow County Sheriff's Office said Wednesday.

Staff Sgt. Cody Wade Smith, 33, was found dead alongside 43-year-old Gregory Thomas Pearce inside the house on Haw Branch Road on Aug. 27.

Smith had returned from a deployment to Europe with Camp Lejeune's 2nd Light Armored Reconnaissance Battalion weeks before, but little had been publicly released about the circumstances surrounding his death until today.

In a press conference, sheriff's office officials said Monica Rose Smith, 32, had served the Marine with divorce papers Aug. 11. Smith arranged to come by her house on the evening of Aug. 27 to drop off some personal property, Maj. Chris Thomas said.

Smith arrived around 5 p.m. with a backpack containing two handguns, duct tape, rope, lighter fluid and matches, Thomas said. He also had a large can of gasoline in his vehicle.

When Monica Smith tried to get the Marine to leave the house around 5:30 p.m., he tied her up, then used her phone to send text messages to Pearce, who arrived at the home half an hour later.

When Pearce discovered Monica was tied up, he tried to call 911, but was shot and killed by Smith, Thomas said. Smith then sprayed lighter fluid on the floor and set the house on fire.

At some point, Thomas said, Monica Smith was able to get control of the handgun used to kill Pearce and fire one shot at Smith, killing him. She then called 911 from the lawn of the burning home and stayed on the line with dispatchers until emergency responders arrived.

All the evidence collected on the scene confirmed her account of what happened, Thomas said.

Monica Smith is not being charged as she acted in self-defense, said Ernie Lee, district attorney for Onslow County.

"Cody Wade Smith did enter the residence with criminal intent," Lee said. "In fact, he had murderous intent."

According to information provided by II Marine Expeditionary Force, Smith was a 15-year Marine who had deployed twice to Iraq and twice to Afghanistan. He had also participated in the 2011 Operation Unified Protector over Libya.

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at@HopeSeck.