father with son in law

i thiiiiink i've got this one. maybe. this is a very vague hypothesis. they're both guilty, the older brother and the construction worker.

here's part 1

the abused mom met the former student of hers and construction worker at the hospital one time she was injured. stress. pain. drugs. something caused her to confide in him about her son hurting her. big guy gets pissed and thinks up a plan. he cases their house, watches it, asks questions, and learns about the son's habits. big guy slips out the back of the bar and kills the abusive son. then he slips back into the bar and his alibi.

part 2 to save face about the whole thing and to shut his mother up the older son kills his mother and lights their house on fire to cover the whole incident up. no mom, no reported abuse or rumors ruining the older son's reputation. remember, he is a bigwig Prefectural Government employee! a reputation is everything to those folks. even a pair of tragic deaths... as long as there is no foul play involved on HIS part... would just be a 'sympathy boost' to his image.

but that's just a very vague idea. i've got nothing to prove it. :/ this one is tricky i think.

i think one of them has a foul mood

these prime suspects hold a deep grudge at being questioned by the police