Marysville police have completed their investigation into the July 6 deaths of Shirley Irene Champagne, 70, and Carrington Michael Costa, 26.
"The final determination was murder-suicide with the grandmother being the shooter," police Cmdr. Robb Lamoureux said Tuesday.
The shooting happened at Shirley Champagne's home at Glenwood Mobile Estates park along 64th Street NE.
The bodies were found early July 6 by her husband, who called 911.
Investigators have not released additional details about what they think happened at the home leading up to the shooting.
Shirley Champagne recently had gone to Florida to pick up her grandson and bring him back to live with her and her husband.
Court records from Florida show that Costa had a history of mental health problems. His family there had called police to report his violent behavior as recently as June.
Police believe Costa was off his medication at the time of his death.
He died from multiple gunshot wounds to the head, according to the Snohomish County Medical Examiner's Office.
The Champagnes moved to Marysville about a year before the shooting.
Family members in Florida did not return calls from The Herald.
Rikki King: 425-339-3449; email@example.com
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