The global security firm G4S is under investigation on contracts for electronic monitoring in the UK valued at more than a billion dollars.  International auditing firm PricewaterhouseCoopers has been called into scrutinize the details of this 2005 deal, which involved G4S and another security firm, Serco. G4S is a mega-player in the industry with  an annual turnover of more than ten billion dollars and operations in 125 countries, including the US. Allegations include overcharging to an extent that according to one source, the cost of monitoring in the UK was more than ten times the figure for the US. While it is too early to determine the result in this case, the incident does remind us that electronic monitoring is big business and that global security firms like G4S (which botched the security for the 2012 London Olympics) and the US-based GEO Group view EM as a future source of enormous profits.  Untapped markets include the more than four million people on parole and probation in the US, high school students identified as disciplinary problems and undocumented workers.  Although in many minor criminal cases electronic monitoring may be a welcome relief from a jail or prison sentence, for those marketing the services future clients may more likely come from the ranks of those for whom an ankle bracelet represents an additional, profit-generating control rather than a respite from incarceration.