What recourse does one have against corrupt cops?
It depends on which country you live in I guess, I can only really speak for Australia. Here we have independent commissions against corruption, some specifically against corruption and misconduct in the police forces. The commissions have wide-ranging powers to investigate allegations, and can bring/recommend criminal charges against people they find to have engaged in corrupt conduct. You could make a confidential complaint to such a commission, if one exists in your country/state.