Couple found dead in Belize not killed for theft; Canadian detained: Police Remains of Drew DeVoursney and Francesca Matus were found Monday.

 -- Theft is not believed to be a motive in the suspected murders of an American man and his Canadian girlfriend, a police spokesperson in Belize said today.

Drew DeVoursney, 36, of Atlanta, Georgia, and Francesca Matus, 52, of Toronto, Candana, were reported missing last week. Their remains were found Monday in an "advanced state of decomposition," with DeVoursney's body on top of Matus, according to police. An autopsy ruled that they died of strangulation, though the motive is not known.

Two people have been detained in connection with the case, according to police, who said that one of the two is a Canadian citizen.

In an interview with "Good Morning America" Wednesday, DeVoursney's mother, Char DeVoursney, described her son as "strong" and "brave."

"He just loved people," she said, adding that he joined the Marines following the 9/11 attacks. "He did two tours in Afghanistan and went back after he got out of the Marines, went back as a contractor."

She said that after he returned from Afghanistan, "he was diagnosed with PTSD."

Drew DeVoursney originally went to Belize to buy property with his best friend from the Marines, according to his mother.

She said that at one point he even hoped to "establish some citizenship there."

The mother said it was "very comforting" to know that he was not alone when he died.

She said she hopes "to be able to find out exactly what happened and who did it."

"We want more details," Char DeVoursney said. "That's what I'm hoping for right now."

ABC News' Anne Laurent, Catherine Thorbecke and Courney Connley contributed to this report.