Is a POA still valid if the person holding it has been deported out of the USA?

If a relative/person has a power of attorney in the USA, does it become invalid if they get deported to Mexico? Is there recourse for that person's other relatives to take over the care of the person for whom the deported person was in charge of care provisions? Can the other family members stop the use of a bank card with proof that the original holder is not using it and that the person using it is possibly a signer on the account? Please advise.