This ain't McCulloch's first rodeo. From wikipedia:
In 2000, in the so-called "Jack in the Box" case, two undercover officers, a police officer and a Drug Enforcement Administration (DEA) officer, shot and killed two unarmed black men in the parking lot of a Jack in the Box fast-food restaurant in Berkeley, Missouri. In 2001, the officers told a grand jury convened by McCulloch that the suspects tried to escape arrest and then drove toward them; the jury declined to indict. McCulloch told the public that every witness had testified to confirm this version, but St. Louis Post-Dispatch journalist Michael Sorkin reviewed the previously secret grand jury tapes, released to him by McCulloch, and found that McCulloch's statement was untrue: only three of 13 officers testified that the car was moving forward. A subsequent federal investigation found that the men were unarmed and that their car had not moved forward when the officers fired 21 shots; nevertheless, federal investigators decided that the shooting was justified because the officers feared for their safety. McCulloch also drew controversy when he said of the victims: "These guys were bums." The two men killed, Earl Murray and Ronald Beasley, had prior felony convictions on drug and assault charges.
Seems like cops in St Louis have a long track record of being afraid of something, I just can't put my finger on it.