Deportation

Okay so I have a question(please no judging) my boyfriends brother is getting deported because he got caught speeding and had his social right next to them and the police asked to see it and found out he was illegal. He’s in jail now waiting to be deported most likely tomorrow or tonight. Will they look into his family to see if they are illegal? Yes or no? If he’s 20 years old basically an adult but still lives with them?