On Father’s Day morning, June 16, 1991, four unarmed security guards were shot to death during a robbery at the United Bank Tower in Denver. Scott McCarthy, 21, was one of the four victims; the others were Phillip Mankoff, William McCullum Jr. and Todd Wilson. A lone gunman entered the vault area, killed the guards, and fled with about $200,000. Security tapes and other key evidence were removed from the scene.

Investigators, including FBI agents, eventually arrested and charged retired Denver police officer James W. King, who had formerly worked as a security guard at that bank. The prosecution’s case relied on circumstantial evidence about King’s familiarity with the building; the defense emphasized the absence of direct physical proof placing him at the scene. A jury acquitted King of all charges.

No other arrests have been reported, the money was not recovered, and the murders remain unsolved. Did anyone who worked at the United Bank Tower in 1991 or knew these guards see anything that could help explain what happened that day?