I would imagine they drugged Geary. He says he passed out. Then, possibly Neri did the deed. He is standing outside the door and he and Tom exchange 'looks.'

The family needed to have Geary in their pocket, not the other way around, which is the way Geary wanted it. And as Tom says, "all that's important is our friendship"....and the fact that we can hold a woman's death over your head.