Como dizer "Chefe de polícia" em inglês

Sheriff?

Talvez esteja relacionado com um antigo cargo... "Condestável".

May Commissioner Gordon helps us???

Despite being a fictional character Ithink he works as a kind of "chefe de polícia". Am I right?

merriam-webster
constable
4 a : a public officer responsible for keeping the public peace and for certain petty judicial duties b Britain : a policeman of the lowest rank

Constable seems common in the UK, but in the USA it is usually applied to a small town police officer. I am not sure if California still has them, but they did when I was a kid. In some places, "the sheriff" is the local police. In California, the sheriff department is a county-level police organization. It is responsible for (or has jurisdiction over) those parts of the county that are unincorporated (not yet full-fledges cities) and those small cities that have chosen NOT to have their own police but to outsource the job to the sheriff department.

Translating is not an easy job. We need to take into consideration a lot of things: politics, history, geography, etc.