ICE is ultimately responsible for any deaths in their custody because once you arrest someone, YOU are responsible for their health and safety until you either release them or hand them over to another legal jurisdiction.
You are also responsible for the actions of your contractors, since you hired and paid them. "Keep them warm, keep them fed, and don't let them die" is an absurdly low bar for any contractor to carry out.
"ICE says its officers can forcibly enter homes . . . "
I've got a gun that says they can't.