A new judge has been named to preside over the trial of reputed Boston gangster James "Whitey" Bulger, a day after the previous judge was removed to eliminate any appearance of bias.

The clerk of the federal court Friday announced the appointment of U.S. District Judge Denise J. Casper.

On Thursday, a federal appeals court removed Judge Richard Stearns from the case, citing his background as a former federal prosecutor. Stearns worked that job in the 1980s, when Bulger was working as an FBI informant while allegedly committing crimes, including murder.

Casper also worked as a federal prosecutor in Boston, leading the U.S. attorney's drug unit. She later oversaw daily operations at the Middlesex District Attorney's office.

Casper, who was confirmed in 2010, is the first black woman to serve on the federal bench in Massachusetts.