Prosecutors from Cook County, Chicago are looking for additional cases of corruption surrounding a former Chicago police officer, the Chicago Tribune reported on Monday.

Prosecutors alleged that there may have been more compromised convictions involving Sgt. Ronald Watts and his subordinates stretching back almost 10 years — far more than the four drug convictions that were previously overturned.

The court has so far tossed out cases involving three defendants and awarded $US2 million to two officers who said they were victimized after initiating their whistleblower lawsuit, in which they alleged they were “blackballed” for attempting to bring Watts’ alleged corruption to light, the newspaper reported.

Watts, a public housing officer, was known to extort protection money from drug dealers and framed cases on those who wouldn’t comply, Chicago Tribune reporter Jason Meisner wrote. He was arrested in 2012 by the FBI and pleaded guilty to stealing money from an informant. He was eventually sentenced to 22 months in prison, according to the Tribune.

“We know from law enforcement documents that Watts and his crew were accused of taking kickbacks on a weekly basis,” said attorney Josh Tepfer of the University of Chicago Law School’s Exoneration Project in an interview with the Tribune.

“It was clear as day that they were routinely framing individuals for crimes that they didn’t commit. And individuals at the highest levels of CPD were aware of this misconduct.”

Ben Baker, who served almost a decade in prison, was released last year. Lionel White, who pleaded guilty to a five-year sentence in order to prevent receiving a potential life sentence, maintained that he had been framed and had his conviction dismissed in December after being behind bars for 2 1/2 years.

“There is little question that [those cases] barely scratch the surface of the wrongful arrests, prosecutions and convictions at the hands of an individual the Cook County State’s Attorney’s Office now acknowledges is a ‘dirty police officer,'” a November filing stated. “The interests of justice necessitate a full accounting of all the victims that have been harmed by wrongful conviction through the actions of these rogue Chicago police officers.”

Tepfer believed that the Watts case was the first time that the state’s attorney’s office was searching through convictions on its own personnel.

“We’re very pleased that they have decided to go forward,” Tepfer said, according to the Tribune. “It’s absolutely the right thing to do.”

“Whether they spent a year behind bars or five years, it was time taken out of society, time where they weren’t able to work, where they lost time with their family or weren’t able to live their life because they were framed,” he said.

“Every one of those individuals has the right to have their convictions overturned and the opportunity to get compensation from the state.”

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