Of all the 60 witnesses who testified before the Ferguson grand jury in the case of the fatal shooting of an unarmed Michael Brown, one offered a particularly vivid account that bolstered police officer Darren Wilson’s version of events.

Brown, the witness said, “dived in” to Wilson’s patrol SUV, “lunging” into the car till he was waist-in. She said she saw Wilson “getting punched by Brown,” and that Brown’s fist “kept going up and down.” She said Brown was “running right at the cop like a football player, head down.”

But the woman turns out to have made some, if not all, of it up, according to court documents released by the St. Louis prosecutor’s office. Her name was redacted.

(Related: Unorthodox police procedures emerge in grand jury documents)

First a federal prosecutor, whose interview with the woman was played for the grand jury, and then county prosecutors who brought the woman in twice to testify, poked holes in her story.

They also got her to admit she has made comments, that she said would be considered “racist.” Comments such as: “They need to kill the [racial epithet]. It is like an ape fest.”

Why even call someone so apparently unreliable and with a dubious motive to testify – and call her back a second time? Some experts say that in a high profile case like Ferguson, the local prosecutor would be remiss if he did not bring in every potential witness.

(Read: Darren Wilson’s full grand jury testimony)

“You have a racially charged case being watched by the entire world,” said Mark Schamel of Womble Carlyle, a criminal defense lawyer who specializes in representing law enforcement officers in use-of-force cases. “If the prosecutor doesn’t turn over every rock, follow every lead, present every piece of evidence, then you’re going to be second-guessed from here to eternity.”

Her account was certainly colorful: After getting lost while driving and looking for a friend’s apartment, she parked her car to ask for directions and saw the altercation between Brown and his friend, Dorian Johnson, and Wilson, who was in his SUV. After the officer exchanges words with the men,“the next thing I know, Mike Brown was lunging into the car, like dived in and it was only from the waist up that he was in the car,” inside the driver’s window, “to about his belt, navel,”  she said.

She said she muttered to a bystander, “Is he f——g crazy?”

Then she said she saw Wilson being punched repeatedly by Brown “You knew he was getting hit, even though he was all the way back.”

“And then I heard the gun go off.”

Johnson “took off running and the heavier-set one that they call Mike Brown stood up, and I seen him pull his shorts up and take off running,” she said.

“The officer got out of the car and had his left hand on the left side of his face and the gun in his right hand,” she said. “And his right hand was shaking, and he was stumbling from one foot to the other, and I don’t know what he said. All I heard was, ‘or I’ll shoot.’ “

Then, she said, that’s when Brown “turned around and face-to-face with the officer, and he had his hands out extended …kind of like, you know, ‘What are you going to do?’”

Wilson had his gun drawn and pointed at Brown and that’s when “Brown started to charge…kind of like a football, like this, with his hands out,” she said, clenching her fists.

“It was kind of like a football charge…and that’s when the gunshots started.”

She said she doesn’t remember the sequence, but the gun went off a couple of times, stopped, then went off again.

Brown “just looked like he was on something….The officer just started shooting him and he didn’t do anything. He didn’t flinch, he didn’t wiggle …and he just didn’t stop, he just kept going.” And, she said, “there was a lot of blood.”

“And then when the last gunshot went off, which was in the head, that’s when I started to get freaked out and I got in my car and I left,” she said.

The federal prosecutor and an FBI agent who were interviewing pressed on why she waited five weeks to come forward.

“Honestly,” she said, “this may sound corny, but I did a lot of praying.”

She said she eventually came forward because she thought of her dad, who told her, “you were always to speak the truth and if you know something, then you are to come forward.”

The prosecutor probed her account of wanting to visit a friend, of sending her friend an e-mail to tell her she’d gotten lost. “Do you still have that e-mail?” the federal agent wanted to know, and also asked for the friend’s e-mail address and phone number.

The agents also asked to look at her computer. “What if we looked at your search history, were you doing a lot of reading about the case and looking at articles about it?”

She acknowledged she looked online at articles to remember things she might have forgotten.

After a break, the federal agents come back and let her know they had been through her online account, “especially the news articles we just showed you,” said one. “I know there’s so much been going on in the community around here and people that just want to help in either way. …[But] what you told us sounds a lot like what we have read in the newspaper.”

The woman objected: “I haven’t read any of that, I swear to God on a stack of Bibles. I looked at pictures to try to figure out which way left the neighborhood and where I was parked.”

One of the federal officials informed her that investigators also pulled “pictures of any cars that would have been going down the street when all of this happened that day. There doesn’t appear to be any car that matches the description of your car. That was another concern that we had as it appears that this car was not there at the time that this happened.”

At one point the federal prosecutor said: “You are better off not saying a word and just not talking to us if you plan on lying and sitting in here and telling us lies.”

The county prosecutors also tried to truth-squad her account. They elicited from her the revelation that she did not go to the neighborhood to meet a friend. Rather, she said, she likes to go into a “random black neighborhood” to, for instance, “strike up a conversation with an African-American …because I’m trying to understand more.”

She acknowledged she was “bi-polar” and she suffered from “mania.” She also said, “I have feelings that others consider to be racist, yes.”

Finally, she admitted that her recollection of Wilson talking to Brown and Johnson was “what I read online and not what I seen.”

One of the prosecutors pressed her: “You feel like you need to help the officer– is that why you’re here? You want to make the officer look better than he looks and make Michael Brown look like a [racial epithet]?”

“All I want is the truth, no, no,” she said.

“I know it sounds like I’m lying,” she said.

“I don’t think you are lying,” responded one of the prosecutors. “I believe you are confused. I think you are confused.”

Erwin Chemerinsky, a University of California at Irvine law professor, said juries and grand juries often are presented witnesses who make conflicting statements. And they must determine the credibility of the witness.

When the prosecutor expresses skepticism about a witness’ credibility, as happened here, “grand juries tend to be skeptical, too,” he said. “Prosecutors have enormous influence over the grand jury.”