A convicted hacker was reportedly paid $75,000 a year by the US Secret Service to operate undercover and inform on bank card thieves.
According to Wired, Albert Gonzalez was eventually arrested in 2008 for running his own version of a multimillion-dollar card-hacking operation.
"That information is according to one of Gonzalez's best friends and convicted accomplices, Stephen Watt," wrote Wired's Kim Zetter.
"Watt pleaded guilty last year to creating a sniffer program that Gonzalez used to siphon millions of credit and debit card numbers from the TJX corporate network while he was working undercover for the government."
Meanwhile, former federal prosecutor Mark Rasch told Wired that $75,000 was a "significant amount of money" but not an "outrageous" sum if Gonzalez consistently delivered "good" results.
"It's probably the only thing he was doing - other than hacking into TJX and making millions of dollars."
Federal prosecutors have accused Gonzalez and two foreign co-defendants of leveraging a number of hacking techniques, including "wardriving," or cruising through various areas with a laptop computer searching for vulnerable wireless Internet signals.
Once a vulnerable network was detected, Gonzalez and his team reportedly installed "sniffer programs" to capture credit and debit card numbers as they were transferred to a retailer's processing computers.