The police would need to see some evidence of at least one incident of hostility; derogatory language; excessive violence; cruelty, humiliation, degradation.
I'm not sure that saying they don't like foreigners is a crime. It's not nice, it is hurtful and some thoughts should be kept to oneself but that one sentence is not enough. Ignoring a person because of their race is not in itself a crime unless it is obvious enough and in a situation to be humiliating or cruel.