You raise a good point, but one of the articles I read stated that the back door was also an entrance into the daughter's bedroom. Apparently this was neither a large duplex, nor a normal residence layout. The police apparently thought it was another door into the residence they had a warrant for, and for all we know, at one time may have been. But it would help explain why his gun was in that room. Further, I've seen nothing that would indicate this young man had any sort of criminal record. I can't help but hope there's something wrong with the information being put forth.
That sticks in my mind, as well.
If he did have a record, stating that fact in the story would interfere with the leftist anti-cop agenda of most of the MSM...