Mr. Costello (first name unknown) is the father of Cookie Costello, who was violently raped and stabbed by Sal Muñoz. Mr. Costello would always bring the dress Cookie wore during the attack to Muñoz’s parole hearings to argue against his release.
Muñoz was up for retrial on grounds of procedure, and part of the defense was a smear campaign against Cookie doe to her bookmaking record and her affair with Bobby Farina, the father of her baby she hid from her family and lost in the attack, leading the defense to paint Farina as a suspect.
Mr. Costello tried to stay stoic and protect Cookie, but Muñoz was acquitted. (L&O: "Remand")