Serco CEO Steps Down Amid Overcharging Scandal (LONDON) - The chief executive of security firm Serco has stepped down after the company was accused of overcharging the British government on contracts to monitor offenders using electronic tags. CEO Christopher Hyman said Friday he was quitting so the company could focus on "rebuilding the relationship with our U.K. government customer." Ed Casey, who led the firm's Americas division, has been appointed acting group CEO. In July, Britain's attorney general said two firms, Serco and G4S, had charged the government millions for people they were not actually monitoring. In a few cases, offenders they were supposedly monitoring were dead. The Serious Fraud Office is investigating, and Serco also faces allegations about its prison escorting contract. The revelations prompted the government to review all contracts held by Serco and G4S.