It's actually Danziger, apparently Columbo incorrectly calls him Danzinger all through the film.
I don't know if i'm thick but couldn't he have said at the end that he was just trying to frame the musician,which he was, better to be convicted of that than murder? I can't remember all the fine plot details though.

Although the gloves are a huge key Columbo would have kept after him because of the feather. But a wise defense attorney could probably get him off.

One bigger problem is Mrs. Danzinger. She is controlling and would badger her husband the same way as Columbo. All the way back to LA. It certainly would be a mentally miserable trip for Danzinger.

Agreed, he hung himself with planting the gloves. Columbo knew because of the feather, but it was not definitive proof such as a fingerprint.