Ferguson prosecutor Bob McCulloch admitted on Friday that he had, in fact, knowingly presented false evidence to the grand jury investigating police officer Darren Wilson for fatally shooting unarmed teenager Michael Brown.

In an interview with St. Louis-based KTRS 550 AM, McCullough said that some of the witnesses called were “clearly not telling the truth,” but testified anyway.

“Early on, I decided that anyone who claimed to have witnessed anything was gonna be presented to the grand jury,” McCulloch said. “And I knew that no matter how I handled this, there would be criticism of it. So if I didn’t put those witnesses on [the stand], then we’d be discussing now why I didn’t … even though their statements were not accurate.”

One of those witnesses, Sandra McElroy, testified that she saw Brown charge at Wilson “like a football player, head down,” a detail that those supporting Wilson, especially Fox News, touted as justification for Wilson using deadly force. McCullough admitted in the interview that McElroy “clearly wasn’t present when [the shooting] occurred” but was allowed to testify anyway.

An investigation by The Smoking Gun found that McElroy suffers from bipolar disorder and is not receiving treatment, has a history of making racist remarks, admittedly suffers from memory problems stemming from a 2001 car crash, and was “no where near Canfield Drive on the Saturday afternoon Brown was shot to death.”

McElroy claimed she watched the events of the shooting, but did not immediately provide police with an eye-witness account of what happened. Instead, she waited four weeks and contacted the cops on September 11. By this time, Wilson’s version of the events had already been reported extensively by the press. She had also repeatedly used her Facebook account to show her thoughts on the case in August, “liking” posts that discussed Brown stealing cigars, and writing that the claims of Brown being shot with his hands up were false. She also posted a comment saying “Prayers, support God Bless Officer Wilson.”

After meeting with police, McElroy wrote on Facebook that “There [sic] great great great grandpa may or may not have been owned by one of our great great great grandpas 200 yrs ago. (Sarcasm).” She also posted a graphic that showed Brown lying dead in the street, with text reading “Michael Brown already received justice. So, please stop asking for it.”

Under the Missouri Rules of Professional conduct, lawyers are prohibited from presenting “evidence that the lawyer knows to be false,” ThinkProgress reported. McCullough defended allowing McElroy to testify, claiming that the grand jury did not take her statements seriously. This is a claim that McCullough cannot make as it is purely speculation. He was not allowed to be present for the jury’s deliberations, as they are required to be secret under Missouri law.

State Rep. Karla May has called for an investigation into McCullough’s handling of the case, saying that he “manipulated the grand jury process from beginning to ensure that Officer Wilson would not be indicted.”

If Maura McShane, Presiding Judge of the 21st Circuit, agrees with Rep. May, she could decide to start the whole grand jury process over again. Double jeopardy would not apply here, because Wilson was never even charged, let alone tried for Brown’s death.

Listen to McCullough’s full interview with KTRS.