The imprisoned musician's legal team wrote in a court filing that he and his representatives were aware of the investigation into Judge Genece Brinkley's conduct since 2016. They argued that the existence of a probe raises questions about the judge's ability to fairly preside over the case.
"How could she sit in judgment? She can't," said defense attorney Joe Tacopina, who declined to answer questions about the defense team's new claim.
An FBI spokeswoman said the agency does not confirm or deny investigations. The judge had no comment.
Mill's lawyers filed the motion days after the judge denied a request to free him in a court opinion in which she wrote he is "a danger to the community."
The judge sentenced Mill last month to two to four years in prison for violating probation on a roughly decade-old gun and drug case. The ruling came after a prosecutor and a probation officer recommended that Mill, who's 30 years old, not be jailed.
The judge said she gave Mill multiple chances to clean up his act but he repeatedly tested positive for drugs, failed to heed travel restrictions and was rearrested twice.
"You basically thumbed your nose at me," she told him during sentencing.
Mill's imprisonment was met with resistance from celebrities, activists, newspaper opinion pieces, billboards and bus ads and a flurry of legal filings that asked for Mill to be freed and for the judge to recuse herself.
The appeals charge that the judge has made the case personal and has wrongly assumed an "essentially prosecutorial" role.
In one instance, they allege, the judge suggested Mill record a version of the Boyz II Men song "On Bended Knee" and mention the judge in it. This interaction occurred in the judge's chambers, and a transcript is unavailable.
The appeals also said the judge "stepped out of the proper judicial role" by visiting a site where Mill was doing community service.
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