Maureen is a one-shot villainess from Diagnosis Murder. She appeared in Season Eight's "Bachelor Fathers."
She was played by Amanda Wyss.
Maureen is the evil sister of the episode's protagonist, Grace Byrd, and the aunt of Grace's son, Casey. She had stolen $466,000 from a pair of drug dealers, Preston Fontenot and Tate Boudreau, leading to the pair targeting the sisters. After only paying back $106,000, another encounter ensued, leading to Tate accidentally killing Maureen.
In a shocking twist, not only was Maureen alive, but she was in league with Preston, revealing her villainous role when she appeared to Grace and pointed a gun at her. She and Preston set up Tate, and they killed him when Grace figured things out. After the reveal, Maureen stated her bitterness over Grace refusing to lend her part of their mother's inheritance, and it was at that moment that Jesse smashed the glass door and pursued Maureen. Maureen regained the gun from Grace, but she was stopped and arrested by Steve Sloan.