ST. LOUIS (AP) — The top prosecutor in St. Louis said Friday that her "exclusion list" of officers who will not be permitted as primary witnesses in criminal cases was requested by the police department itself.

Circuit Attorney Kim Gardner's list of 28 officers, announced Thursday, raised concerns from police union leaders and Missouri Attorney Josh Hawley. Gardner has not detailed what specifically landed the officers on the list, citing only credibility issues.

But on Friday, she took exception with the notion that police were unaware of the list. Gardner and her spokeswoman said prosecutors had conversations with police leaders over several months.

"After prosecutors discussed the specific officers about which they had concerns, the SLMPD (St. Louis Metropolitan Police Department) asked for a physical list, which was subsequently sent to them," Susan Ryan, Gardner's spokeswoman, said in an email.

Police declined to comment. But chief John Hayden seemed surprised by the list on Thursday, saying in a statement that the department was "seeking legal guidance" on how to proceed.

Public Safety Director Jimmie Edwards said the circuit attorney has not provided details about why the officers are on the list. Edwards said several listed officers are no longer with the department, but did not say how many.

Hawley, in a letter to Gardner, wrote that it is "imperative" that she provide him with the names of the officers "and the grounds for their inclusion." He said Thursday he was worried that Gardner's action could raise the risk of more crime.

Gardner said prosecutors will work with police "to do everything possible to ensure violent offenders are held accountable, regardless of the role any of these police officers may have had in the gathering of evidence."

Prosecutors will pursue open cases in which the listed officers were involved as long as they can be proven without those officers' testimony, Gardner said.

"Proving a crime beyond a reasonable doubt in a court of law requires credible evidence. Police testimony is only one form of evidence," she said.