Sandra McElroy, a key Ferguson witness whose testimony to the grand jury that eventually exonerated Officer Darren Wilson in the killing of unarmed teen Michael Brown, has been among the most often cited in the media, simply made up her whole story, a new investigative report finds.

The new report calls into question the integrity of the grand jury process in the Ferguson case, because court documents show that prosecutors and federal investigators knew McElroy’s tale of witnessing the confrontation between Brown and Wilson was fiction.

In fact, it now appears that McElroy was not even at the scene of the shooting at all.

But prosecutors allowed her to testify not once, but twice, entering a “journal” she kept of her phony “eyewitness account” as evidence in the case. The Inquisitr reported earlier on McElroy’s false testimony, when she was known simply as “Witness 40,” in a story that can be accessed at this link.

The investigative report was carried out and published by The Smoking Gun, an investigative news site that has been on line since 1997 posting legal documents on the web. The site is owned by the cable network TruTV, which is part of Turner Broadcasting.

The Smoking Gun found that McElroy was the previously unidentified “Witness 40,” who by her own admission is a “racist” and “bi-polar,” and whose testimony was attacked and discredited repeatedly by prosecutors and federal agents who were conducting a civil rights investigation into the August 9 killing of 18-year-old Brown by Wilson.

McElroy, a 45-year-old resident of St, Louis and mother of five, confirmed to The Smoking Gun that she was indeed the “Witness 40,” whose claim that she saw Brown charging at Wilson “like a football player, head down” has been repeatedly cited in the media.

The account has been cited perhaps most often by Fox News personality and nationally syndicated radio host Sean Hannity, whose frequent repetition of McElroy’s “football player” account was documented by a rival TV news talk host.

Even though police found no evidence that McElroy was ever at the Canfield Drive scene of the shooting, the so-called “Witness 40” was put in front of the grand jury not once but twice.

Her incendiary description of the entire confrontation between Brown and Wilson — which she claimed to have witnessed while standing on a nearby sidewalk smoking a cigarette, has been “baked into the narrative of the Ferguson grand jury,” the Smoking Gun reporters wrote, “a panel before which she had no business appearing.”

In fact, McElroy had a history of giving false witness statements to police.

In 2007, after a St. Louis boy named Shawn Hornbeck was rescued from a kidnapper, Michael Devlin, who had held him captive for years, McElroy concocted a story about having known Devlin and seen Hornbeck with him.

She went so far as to claim that she told police that she had seen the two together not long after Hornbeck vanished in 2002. The police said they had no record of any contact with McElroy, and condemned her allegations as “a complete fabrication.”

Nonetheless, Sandra McElroy, with her colorful and shocking account of an out-of-control, monstrous Michael Brown furiously attacking Darren Wilson until the officer was forced to kill him, has become the media’s most popular Ferguson witness.