Death in custody is when a person dies while they are being held by the police, in a prison or other place where they are being watched. It can happen if someone is injured while they are in custody, or if they get very sick and there is no one to help them get better. People can also die if they are not treated properly while in custody, such as not getting enough food or water. Death in custody is a very serious issue, and the police have to be extra careful to make sure it does not happen.