A former gang leader and one-time FBI informant accused of stabbing former Minneapolis Police officer Derek Chauvin in federal prison pleaded not guilty to related charges Friday. 

John Turscak, who is serving a 30-year sentence for crimes committed while a member of the Mexican Mafia prison gang, is accused of attacking Chauvin with an improvised knife in the Federal Correctional Institution in Tucson, Arizona, around 12:30 p.m. on Black Friday, the day after Thanksgiving.

He was charged with attempted murder, assault with intent to commit murder, assault with a dangerous weapon, and assault resulting in serious bodily injury two days after the Nov. 24 attack on Chauvin, who is serving out a more than two-decade sentence in connection to George Floyd’s death.

Turscak, accused of stabbing Chauvin 22 times in the attack allegedly inspired by the BLM movement, pleaded not guilty during a Friday court appearance.

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His jury trial is currently scheduled to begin Feb. 13.  

The alleged incident happened just four days after the U.S. Supreme Court declined to hear Chauvin’s appeal of his murder conviction. Separately, Chauvin is making a longshot bid to overturn his federal guilty plea, claiming new evidence shows he didn’t cause Floyd’s death on May 25, 2020. 

In a statement released on Dec. 3, Chauvin’s attorney Gregory Erickson said, “Derek’s family confirmed that his medical condition has improved to the extent that he has been removed from the trauma care facility at a local Tucson hospital and returned to prison custody for his follow-up care.”

Erickson added that the Chauvin’s family “is very concerned about the facility’s capacity to protect Derek from further harm,” and that “they remain unassured that any changes have been made to the faulty procedures that allowed Derek’s attack to occur in the first place.”

Turscak told FBI agents interviewing him after the assault that he attacked Chauvin on Black Friday as a symbolic connection to the Black Lives Matter movement, which garnered widespread support in the wake of Floyd’s caught on camera death in 2020, and the “Black Hand” symbol associated with the Mexican Mafia, prosecutors have said. After the stabbing, Turscak was moved to an adjacent federal penitentiary in Tucson, the Associated Press reported last month, citing inmate records. 

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Chauvin, 47, was sent to FCI Tucson from a maximum-security Minnesota state prison in August 2022 to simultaneously serve a 21-year federal sentence for violating Floyd’s civil rights and a 22½-year state sentence for second-degree murder. Chauvin’s lawyer at the time, Eric Nelson, had advocated for keeping him out of the general population and away from other inmates, anticipating he would be a target. In Minnesota, Chauvin was mainly kept in solitary confinement “largely for his own protection,” Nelson wrote in 2022 court papers. 

Turscak led a faction of the Mexican Mafia in the Los Angeles area in the late 1990s and went by the nickname “Stranger,” according to court records. He became an FBI informant in 1997, providing information about the gang and recordings of conversations he had with its members and associates.

The investigation Turscak was aiding led to more than 40 indictments. but about midway through, the FBI dropped Turscak as an informant because he was allegedly still dealing drugs, extorting money and authorizing assaults. According to court papers, Turscak plotted attacks on rival gang members and was accused of attempting to kill a leader of a rival Mexican Mafia faction while also being targeted himself.

Turscak pleaded guilty in 2001 to racketeering and conspiring to kill a gang rival. He said he thought his cooperation with the FBI would have earned a lighter sentence.

The Associated Press contributed to this report.