The series premiere for CBS' Yellowstone spinoff Marshals confirmed that Kelsey Asbille's character Monica had been killed off. During the Sunday, March 1, series premiere, Kayce (Luke Grimes) was introduced with son Tate (Brecken Merrill) but wife Monica was nowhere to be found. Through context clues, it was established that Monica died after the events of the Yellowstone spinoff - presumably from a cancer battle. Her death was linked to Tate joining an anti-mining protest on the grounds that the side effects lead to health risks for those on the reservation in Montana.