Mortgage for life? I never heard of that! Is that why they mentioned the 500,000 home they just bought before he was killed?
Not "mortgage for life" - "mortgage life" - i.e. you take out an insurance policy that pays enough to pay off your mortgage if you die, so your family won't have to worry about mortgage payments.
You've never heard of "mortgage life" insurance? It pays off the loan in the event of the death of the mortgage holder(s). In this case, they were probably both on the mortgage, but the death of either one would pay off the loan. If they had such a policy, it certainly would provide motive.