Whether Bulger has immunity is a crucial question as he awaits trial in June on charges he participated in 19 murders, The Boston Globe reported Wednesday.
In a filing in federal court late Wednesday, prosecutors revealed a jailhouse telephone conversation Bulger had with his brother John in September 2012.
"I bought [expletive] information, I didn't sell it," the 83-year-old Bulger said. "I never gave them [expletive] information. Nothin'. Nothin.'"
Prosecutors want a judge to rule on Bulger's claim he was granted immunity for all his crimes by a former federal prosecutor who died in 2009. Bulger wants a jury to determine his immunity during his trial.
The jailhouse conversation proves Bulger didn't have immunity, prosecutors argue, because if he did he wouldn't have had to pay off FBI agents.
Bulger was captured in Santa Monica in June 2011 after being on the run for more than 16 years.
He fled just before being indicted in 1995 after being tipped off by a now-imprisoned former FBI agent, John J. Connolly, Jr.