What would be the phrase or proverb or idiom for "A robber is recognized or appreciated by a thief"?

What would be the phrase or proverb or idiom for "A robber is recognized or appreciated by a thief"?

For instance, a jailbird criminal is supported/helped/appreciated/awarded by a corrupt politician or vice versa etc.

Solution 1:

Birds of a feather flock together

Prov. Similar people tend to associate with each other. I always thought Amy was pretentious, and now she's going out with that snobbish boy, Louis. Birds of a feather flock together. George: Why do you think Donald is dishonest? Ned: All his friends are dishonest. Birds of a feather flock together.

McGraw-Hill Dictionary of American Idioms and Phrasal Verbs