You know what is a definite possibility here (I have no inside information), and just a possibility: the suspect is a friend or associate of Patsy and Patsy was covering for this person and giving him/her an alibi to avoid the embarassment from the prosecution and trial of a friend. Now that Patsy is dead, she can no longer be embarassed and cannot cover for this friend/associate, which is why the arrest is happening now. This fits with the facts of the case, which IMO do not support the unknown intruder theory.
This will be real interesting to see who they arrest.