It’s also possible for the police department to totally ignore that subpoena and come to court empty-handed, and for the judge to tell the defendant: “I don’t give a shit about all your subpoenas! Guilty as charged!”
I witnessed that one day in a case I observed. It did seem (to me) that the defense lawyer was just on a wild fishing expedition, he had subpoenaed so much stuff, and the judge wasn’t buying it.