In Payback (2021), at 25:51 the dialog goes like this --
Mickey: Mr. Strauss, I didn't do this. Slava sent me to the store. Ruslan killed those men.
Strauss: Are you prepared to testify to that?
Then the movie shows that Mickey comes back home after spending six years in prison. That means, he didn't testify.
So, the question is: Why didn't Mickey testify?