Beckett, meanwhile, maintained during the trial that Letts' death was either suicide or an accident.
Letts admitted to having suicidal thoughts in a 2007 diary entry.
The court heard Letts went into the water while she and Beckett were on an evening boat ride near Shelter Bay provincial park campground. She was not wearing a life jacket and was not a strong swimmer.
Lawyers are expected to return to court on September 19 to address logistical issues with a potential change of venue, and hear whether a hearing will take place. Beckett has been in custody since his arrest in 2011.
In April, following his first trial, he labelled the court he stood trial in a "kangaroo court".
"I've been disgusted with the whole Kamloops kangaroo court from the get-go," the 59-year-old told KTW in a jailhouse interview after his jury returned hung.
"You can't convict a guy of first-degree murder based on the Crown's theory that he lied. Kangaroo court doesn't even begin to describe what goes on in Kamloops," Beckett said.
- Kamloops This Week