Who Killed Siegel White Collar

What are everyone's thoughts on david siegel? Initial opinion was i didn't like him because he was going to split the neal/peter team but quickly that changed because he is charming. At the end of the episode, it is revealed that rebecca murdered david siegel and hagen, and rebecca was never actually kidnapped, so she was working with hagen the whole time. Peter blames himself for siegel's death because peter brought him in to new york to replace him as neal's handler. Elizabeth trusts peter but.

Peter comes to the conclusion that rebecca killed agent siegel when she discovered that he is on.