Hidden Clues

My wife and I are in the process of watching all the old Castle episodes.  The night before last we watched "Almost Famous", written by Elizabeth Davis and Directed by Félix Alcalá.  This is the 41st episode and the 7th of the third season, first airing on 1 November 2010.

The basic storyline is:

Beckett and Castle respond to an "Officer Down" call only to find that the murdered "officer" is actually a male stripper wearing a police costume.

My problem, our problem, is that at the end Beckett and Castle go to the home of a rich widow (a trophy wife) to arrest her for the murder of the stripper and when they arrive they almost immediately go for her lawyer as the murderer.  So, what happened in the car during the ride over that caused them to refocus their attention?

Regards  —  Cliff