BBM
As for the beer can; even if there are prints on it LE will not just assume that it is the murderers' fingerprints. There would have to be other indicators pointing toward that person as well, IMO, for LE to even begin to think that the prints and/or DNA belonged to the murderer. It could just be an attempt to frame someone.
Of course, figuring out who would want to frame the beer-can-fingerprints' owner would be helpful, too.