Brimmer was indeed guilty of involuntary manslaughter. If he kept his cool he could have had the victim charged with criminal trespass.
Brimmer would have also been charged with abuse of corpse for dropping off the dead body and probably hindering apprehension.
Outside chance he could have received probation based on his lack of criminal record, but he more than likely would have received jail time.
More than likely the latter mentioned charges in conjunction with the involuntary manslaughter offense would have sunk his chance of a probation sentence.