Phillip Mankoff, a 41-year-old father of four, was one of four security guards murdered during the Father’s Day Bank Massacre at the United Bank Tower in downtown Denver on June 16, 1991. Mankoff, who lived in Aurora and also worked for Child Support Services, was shot and killed after an armed intruder used a stolen or falsified access method to reach the bank’s underground security and vault areas. Investigators reported the gunman fired 18 shots, that 17 struck the victims, and that the killings appeared deliberate and planned.

The assailant collected videotapes, keys, a radio, and parts of the security log after the slayings, then forced bank employees in the vault area to load roughly $197,000 before escaping. Witnesses described a well-dressed man in a hat, mirrored sunglasses, a mustache, and a bandage on his cheek; ballistics tied the shootings to a .38-caliber revolver believed to be a Colt Trooper.

Authorities later arrested a retired Denver police sergeant who had worked at the bank; prosecutors relied largely on circumstantial evidence and eyewitness IDs, while the defense challenged the reliability of those identifications and pointed out the lack of direct physical evidence tying him to the scene. Did anyone who worked at United Bank in 1991 or who knew Phillip Mankoff recognize any detail that might help reopen questions about what happened that day?