OK, suppose for the moment that Wilson's shooting was justified.

[Jackpine Radical]

4. OK, does this help?

(Apparently I, along with half the media, have been misspelling McCulloch's name)
Quotes from Wikipedia

Here's where he inappropriately helped the cops identify a whistlebolwer in their ranks

In 1997, in the so-called "Kinkogate" case, McCulloch gave - using the power of the grand jury, but without informing it - a subpoena to the police in order to identify a whistleblower who was acting lawfully. He first claimed the fax contained a threat but later conceded that there was no threat and no crime, but denied any wrongdoing. The whistleblower had to quit his job.[3]

Here is where he previously covered up a cop killing:

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.[2][4] 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.[3] 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.[2][4] McCulloch also drew controversy when he said of the victims: "These guys were bums."[2] The two men killed, Earl Murray and Ronald Beasley, had prior felony convictions on drug and assault charges.[2]

There's more if you need it.