Mark Hasse was 57 and the Assistant District Attorney for Kaufman County, Texas, when he was shot and killed on January 31, 2013. He was attacked in broad daylight while walking from his car to the courthouse in Kaufman; a masked gunman dressed in black shot Hasse multiple times and fled in a waiting car.

The investigation involved local and federal agencies. Early speculation pointed toward the Aryan Brotherhood because of Hasse’s work on cases involving gangs and white supremacist groups, but that theory was later disproven. Eric Lyle Williams, a former lawyer and justice of the peace, was implicated in Hasse’s killing as part of a series of murders that also included prosecutors Michael McLelland and his wife Cynthia McLelland. Williams was prosecuted and sentenced to death for the McLelland murders; authorities did not pursue a separate prosecution of him for Hasse after that sentence. Kimberly Irene Kim Williams pleaded guilty to participating in Hasse’s murder, admitting she was the getaway driver, and received a 40-year prison sentence.

Anyone who knew Mark Hasse or has information about his movements that day is asked to share what they remember.