A US Citizen on its way back to the US from the UK heathrow airport was arrested due to a expired visa,?

He went to the Emby and spoke to the consular that he needed istance to return to the US. The consular said they would ist with the airfare on AA. which they did. However during the wait to fly back to the US at the time to check in he was arrested because his visa expired. Now I wonder what will happen to him. Will he be extradited back to the states? Deported back to the States? He went to the Emby in the first place because he did not have enough funds on his own to return home. What will happen to the insured AA ticket that was purchased? How can he get home?