CHICAGO (CBS) — The back and forth between the mayor and the Chicago police union continues, with the city sending out a flurry of emails and memos as its vaccine mandate enters its first full week in effect.

CBS 2’s Mugo Odigwe obtained the latest threatening memo sent out to officers.

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At least two memos have gone out since Friday’s deadline for all city workers to report their vaccination status to the city, but Fraternal Order of Police President John Catanzara said thousands of officers are still refusing to do so.

“The unofficial number we have is about over 3,200; so about of third of the department,” Catanzara said.

Catanzara has said the mandate is illegal, because the city didn’t negotiate terms with the union.

He said officers who are still refusing to report their vaccination status will be called in by supervisors on Monday, and once again will be asked will be asked to comply with the mandate.

“If they refuse, it sounds like they’re going to go into a no pay status, effective immediately,” Catanzara said.

He said the dispute with the Lightfoot administration is no longer about the vaccine, or personal beliefs, but collective bargaining rights.

“All of those things are a change in your employment policies. You have to negotiate with us what that looks like. The city has refused to do that,” Catanzara said.

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Two memos have been sent out since Friday.

The latest, from Sunday, involves consequences officers could face if they don’t follow the city of Chicago’s vaccination policy.

Any such officers will become a subject of a disciplinary investigation that could “result in a penalty up to and including separation from the Chicago Police Department.”

The memo goes on to say that “sworn members of the department who retire while under an investigation may be denied retirement credentials.”

On Saturday, a different memo went out, saying days off now require approval from a deputy chief or above.

CPD hasn’t said if this is related to the ongoing tension between the police union and Mayor Lori Lightfoot over the city’s vaccine mandate, but as of now, the union is not budging.

“Our moniker all week has been hold the line, for a reason,” Catanzara said.

The union has sued the city over the mandate, seeking to force the city to engage in arbitration.

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Basically, Catanzara said both sides are at a stalemate.