The FBI of course giving the credit to their "linguistic analysis team" and "fearless investigators" when Ted's brother literally turned him, told them where he lived, and that he had talked about bombing the targets in question.

Many, if not most, murder investigations are resolved by confessions, or someone turning the culprit in. Absent that, after...I want to say 48 hours, the police know that they should essentially write off the case. There are obvious exceptions, especially if there's public notoriety (crudely, young white coeds or "sexy shit"), but most murders are poor drug addicts murdering other poor drug addicts.

Source: worked 2 years in DC as a freelance reporter, was ultimately not successful there, but soaked up a lot of stories/cynicism