The authorities aren't telling the truth and I don't blame them. They are deflecting attention as best they can (not very well however).
There was a surplus of anger in this killing. Robbery is not the prime mover. Deep seated anger...either misdirected or accurately directed.
But anger is the key.
"But anger is the key."
I'll try it in aussie-speak. Two drop-kicks with form, a history of dealing, they are tenants of a migrant family that is doing quite well financially, hard working, active in community affairs; the rent is high, they are both short of money and they hate immigrants. Of course they are angry, someone else has what they believe they deserve, a nice home and a family. Who did one of them owe money to? How desperate might he have been to repay a loan, what might the penalty have been for not settling this outstanding debt? Was the money owed to a drug supplier? Ouch!
Meanwhile the family is threatened by muslims on a website, the perps were I believe, regular visitors to the family, perhaps the father made the threats known to one of the perps and presto...what a perfect opportunity, we can rob them and sit tight, we don't have to run and draw attention to ourselves, the cops are going to blame you know who anyway...so the worse the bodies look, the less likelyhood there is that the murders will appear to have been part of a robbery. Hey, I could do this all day. I wish I had never heard of it. Let the cops have at it.