The Pt W killings were the last week of Jan, this year. And this article says Ritchie returned from outside in Feb.   Sounds like this guy was out of state, although what little we know, seems to fit with the others. 
Except for the weapon. Seemingly random. Double homicide. No apparent motive. No witnesses or evidence (to which we're privy).  
Although we can be glad he's... no longer a threat...  I'm sure they would have preferred to get him alive, and get him talking.