>Do they also just arrest people based on other 'witness' reports without any effort towards corroboration? Pretty much. They will investigate for alibis and

>Do they also just arrest people based on other 'witness' reports without any effort towards corroboration? Pretty much. They will investigate for alibis and if there are fingerprints/DNA they will do that test. But absent other physical evidence a single eyewitness is good enough. Unsurprisingly they often are wrong. Netflix's Innocence Project has an episode where this happened. A woman was raped and thought she saw her assailant some time later. He was subsequently convicted and eventually exonerated due to DNA evidence. Practically speaking there is going to be at least something else pointing to an accused. Otherwise, they wouldn't be showing that picture to a witness. But once you're suspected the standard is the witness picking the correct photo out of a line up of 6. That's enough to be arrested and often enough to be convicted.