Steven Lawrence Singer, 48, was killed in a workplace shooting in north-central Phoenix on January 30, 2013. The shooting began after a dispute inside an office building when a 70-year-old man, Arthur Douglas Harmon, entered and opened fire. Singer died hours after the attack.

The violence also killed 43-year-old Mark Hummels, who died in hospital days later; a third victim, a woman, suffered non-life-threatening injuries. Authorities later found Harmon dead of an apparently self-inflicted gunshot wound after a search that described him as armed and dangerous. The shooting was reported to have arisen from a dispute at the office complex. Family and friends held a memorial service for Singer at Temple Chai in Phoenix.

If anyone knew Singer, his routines, or was in that office building that morning, any information could help clarify what led to the dispute and the shooting.