I just love statements like this. How much on a limb are police willing to go? They admit it was a home invasion, but they only "believe" that the man shot dead was an intruder. "You know, maybe he was the home owner, maybe he was an intruder, but we believe he was an intruder. We haven't checked the ID yet of the survivor to see if he lived there or not, yet. Things take time, and we don't want to be rash in our judgements until the facts are in."
There are other possibilities. He could have been a hostage, forced into service to gain entry. He might have connections to the homeowner that will be revealed during the investigation.
I admit that those things are unlikely, but they exist, and the police must be very careful about making definitive statements.