Look, I don't want to get all continuity-y on you but Brutus, from what we've been told, only has two living older relatives. Uncle Ted and his mother-in-law, Ramona Gargle. Everyone else related to Brutus lives in his house. Who drove him crazy? He should be used to Mother Gargle and he likes Uncle Ted. Also, Brutus still had to work. He probably only got Christmas Eve/Day and New Year's Eve/Day off if that so he had at least 8 family-free hours away.
And we know Brutus didn't kill them making this a pseudo-confession because we've seen, at least, Gladys since the holidays.