The panel Tuesday heard tapes of Viens, 49, telling sheriff's homicide investigators he panicked when he discovered he had accidentally killed his wife, Dawn, who was 39 when she disappeared in October 2009, the Los Angeles Times reported.
Viens pleaded not guilty to killing his wife, whose remains have not been found.
Viens was interviewed from his hospital bed in 2011, where he was recovering from injuries he sustained from jumping off a cliff after learning he was a suspect.
Viens' attorney, Fred McCurry, has maintained investigators lacked physical evidence about Dawn Viens' fate.
The Times said Viens, in a wheelchair, listened to the recording and either stared ahead or took notes.
David Viens said he put his wife's body into a drum of boiling water, weighing it down to keep it submerged.
"I just slowly cooked it and I ended up cooking her for four days," he told investigators, although it wasn't clear where it occurred.
Then, Viens said, he mixed some of the remains with other waste and poured it into the grease pit at his Lomita restaurant. He said other remains were in garbage bags thrown into a trash bin.
He kept his wife's skull, he told investigators, telling them he left it in his mother's attic. A search turned up nothing.
Viens said he and his wife had gone to dinner, and she returned home while he went to his restaurant then to several clubs with friends. The couple fought when he returned home, although he changed the reason for the fight in his interviews with investigators.
In the interviews, Viens said he put duct tape over his wife's mouth and bound her hands and feet, then went to sleep. When he awoke the next morning, Viens said he panicked.
Asked why by investigators, he replied, "She was hard."
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