In 1990, Clarence Wilson was found guilty of taking bribes to protect drug dealers and other criminals while he was a Chicago cop.

Wilson’s felony conviction — part of the so-called Wentworth police scandal — landed him a 3-1/2-year prison term, of which he served roughly two and a half years.

But the case didn’t end public-sector employment for Wilson in the crime prevention arena.

After prison, he was hired as a security officer for the City Colleges of Chicago — the taxpayer-run community college system.

Wilson, now 82, still works as an unarmed guard at Arturo Velasquez Institute, a satellite campus of Richard J. Daley College. He is paid $17.49 an hour, and told us he is only working a couple of days a week now and considering retirement.

 He’s eligible to collect a taxpayer-subsidized pension that, if he left today, would be worth a projected $660 a month, according to records and interviews.

Wilson told us he doesn’t see the big stink about holding the job and drawing a public paycheck, especially since he said he was innocent in the Wentworth case, which snared a dozen or so current or former cops who were accused of taking payoffs to protect drug dealers and illegal gambling dens from raids.

 “It was [selective] prosecution,” Wilson said. “I’m tired of being a victim.”

The U.S. attorney’s office had no comment.Wilson said he retired from the Chicago Police Department in 1988.

City Colleges records show him starting with the system after his January 1990 conviction and before his September 1990 departure to prison.

Wilson said that sometime after he was released from federal custody in 1993, somebody from City Colleges — he doesn’t recall whom — reached out and asked whether he wanted to come back to work,  an offer he jumped at. He needed a job and had lost his police pension because of the scandal.

He said he’s been at City Colleges ever since. His duties include making sure only authorized employees, students and visitors are on campus, and making rounds as needed.

So why is this coming out now?

A source who asked to remain anonymous said the City Colleges administration was tipped to Wilson’s background by a concerned employee a year or more ago but did nothing.

 In recent weeks, that employee went directly to the system’s inspector general — the in-house watchdog — to complain, sources said. The City Colleges administration, led by Chancellor Cheryl Hyman, also contacted the inspector general around this time, but it’s unclear whose complaint came first, and why there may have been a delay in the administration acting.

Either way, an investigation was launched.

Hyman’s aides wouldn’t answer our questions about this matter — including how much Wilson is being paid annually, how many hours he’s putting in, why they didn’t act sooner — or otherwise comment. They would only say this:

“The safety and security of City Colleges faculty, staff and students remains our first priority and City Colleges is committed to putting the talent in place to provide a secure environment for teaching and learning. City Colleges cannot comment on an ongoing investigation with the Office of Inspector General.”

Inspector General John Gasiorowski confirmed there’s a probe but said he could not yet publicize details, other than to say he plans to wrap up the investigation soon.

Felons are allowed to work for local government under many circumstances, but nobody at City Colleges could tell us whether they’re barred from working security there. Even if they’re allowed, given the nature of Wilson’s conviction — a violation of the public trust —should he be allowed to work for taxpayers again?

The  inspector general investigation is believed to be centering on how Wilson got his job at all.

We have conflicting accounts about whether employee background checks were conducted in the early 1990s.

There are at least several hundred security officers at City Colleges — which includes seven main campuses and more than 100,000 students.

The City Colleges budget describes the Office of Safety and Security, with an allocation of more than $12 million a year, as “a proactive department that concerns itself with crime prevention primarily and reactive response when necessary.”

Neither Gasiorowski nor Hyman’s aides would say whether they’re now taking a look — or plan to take a look — at the backgrounds of other security guards employed by the college system to see whether anyone else raises red flags.

This column was written and reported by the Better Government Association’s Patrick Rehkamp. He can be reached at (312) 386-9201 or prehkamp@bettergov.org. Rehkamp’s Twitter handle is @patrickrehkamp.