Ally Fogg makes a very good point.
The first recourse of the racist fearmonger has always been to point to one atypical incident, a riot, a murder, a rape, and hold it to be typical, to be both representative of an entire population and the responsibility of that entire population. The left cannot win by pretending there are no criminals, no thugs, no rapists, no damaged people among the shifting sands of humanity. We can win by unequivocally condemning inappropriate and criminal behaviour while simultaneously and correctly insisting that we will not allow ourselves to judge the many by the sins of the few. We will not allow ourselves to be distracted and diverted from our humanitarian obligations by fear, because history shows us where that leads. We will not allow ourselves to turn our backs on those in desperate need, because we are smarter than that and we are better than that. That is the only way the argument can be won.
I would add that one thing that’s become obvious is that if you hesitate to condemn an act because the perpetrator is a member of an oppressed group, the racist fearmongers will then turn around and use that to condemn the entirety of the left of conspiring with the group that they hate. It’s what they do, and they’re very good at it — you might even say it is the dominant trait of fearmongers, that they’re adept at smearing everything into a giant category of blame.
It’s one of the things that makes addressing them difficult: anything you do will get you swept up into the burning shitpile of hatred they keep aflame. So you might as well just do the right thing.