Robb faced at least 15 years to life in prison. While awaiting trial she was permitted to write letters from jail to their children.
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The plea comes as the trial date approached and Robb’s not-guilty-by-reason-of-insanity had been rejected by Judge Robert Peeler.
During a court hearing, Peeler said the second psychologist, Kara Marciani, found Robb, 35, knew right from wrong last November when she allegedly shot and killed Jason Robb.
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Peeler had already ruled that Mercedes Robb could assist in her defense.
Under the plea and sentence Wednesday, Robb is to serve at least 25 years before being paroled.
The Robbs were locked in a custody battle, and Jason Robb had cited her diminishing mental condition in a motion seeking full custody.
He was was the owner of J & J Fabricating, developer of a system used to manage video monitors in Costco stores across the country. He had recently launched another business, the Frankenfries food truck.