Another First

At the end of my shift I am called to a assault. A brother versus his sister. The brother gave sister a black eye, during a family barbecue. The brother had too much to drink and the sister was trying to get him to slow down.

The issue is that the brother is a deaf mute. He know sign language and can read some lips, but he won't talk to his brother who is the only one who knows sign language.
I use a pad and paper. He admits to punching his sister.
I have to try to get by with hand gestures and making sure eye I have eye contact.I try to let him know he is under arrest and hope gets most of it.