Updated

Federal prosecutors announced Friday attempted murder charges against an Arizona inmate and ex-FBI informant, a week after ex-Minneapolis cop Derek Chauvin was stabbed 22 times inside a library at the Tucson penitentiary where they are both inmates.

John Turscak, 52, is also facing multiple assault charges and inflicting serious bodily injury with an "improvised knife" around 12:30 p.m. on Black Friday – a day the suspect allegedly told investigators he picked to symbolize the "Black Lives Matter" movement, which spurred months of protests around the country in connection with the death of George Floyd – who Chauvin was convicted of killing.

Federal corrections officers intervened "immediately" according to court filings, dousing Turscak with pepper spray. He allegedly told the guards he would have killed Chauvin if guards hadn't reacted so fast. When he waived his Miranda rights, he allegedly told the FBI about the Black Friday symbolism and said he'd planned the attack for a month.

Prosecutors said that Turscak was an FBI informant in 1997, providing information about his gang as well as recordings of conversations between him, members, and associates. The investigation resulted in 40 indictments, but halfway through, Turscak was dropped as an informant because he was dealing drugs, authorizing assaults, and extorting money.

DEREK CHAUVIN ‘DEAD MAN WALKING’ EVEN BEFORE THANKSGIVING STABBING: FORMER PRISON MINISTER

Derek Chauvin in court

The city of Minneapolis is paying out nearly $9 million in legal settlements to individuals whom former police officer Derek Chauvin knelt on prior to his deadly 2020 confrontation with George Floyd. (Court TV via AP, Pool, File)

He claimed to have targeted Chauvin solely because he is a high-profile inmate – something prison experts warned was likely to happen.

Turscak could see 60 years added to his federal sentence if he gets the maximum punishment on all of the charges he faces. He was due for release in 2026, according to the Bureau of Prisons.

DEREK CHAUVIN STABBED BY INMATE IN FEDERAL PRISON, SERIOUSLY INJURED: REPORT

George Floyd image prior to his death in Minneapolis in May 2020

George Floyd died May 25 after an encounter with four Minneapolis police officers. A Minnesota judge on Friday ordered the release of footage from two police body cameras that captured their encounter with Floyd.  (AP)

Authorities told Fox News Digital it is against their policy to give updates regarding inmate health, citing safety and privacy concerns. 

Prison staff "isolated and contained" the incident before performing "life-saving measures" on Chauvin, who was treated at a hospital outside the prison.

Read the criminal complaint (Mobile users go here)

In an appeal filed last month, Chauvin claimed new evidence shows he was not responsible for the death. Separately, the Supreme Court rejected his appeal for a new trial just days before the stabbing.

Chauvin is serving a sentence of more than 20 years in prison for the 2020 murder of George Floyd.

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Chauvin was one of four officers who arrested Floyd that day after he allegedly passed a counterfeit $20 bill at a coffee shop and refused to cooperate with police.

Chauvin, on widely seen video that prompted riots around the country, knelt on Floyd's neck for more than nine minutes leading up to his death.