Charlottesville, Virginia (CNN) The man on trial for killing Heather Heyer at a white nationalist rally in Charlottesville, Virginia, last year shared two images on Instagram that showed a car hitting protesters months before he did exactly that, according to court documents.

The images were released on Day Two of the trial of James Alex Fields Jr., who is accused of driving his Dodge Challenger into a crowd of counterprotesters during the August 2017 Unite the Right Rally, killing Heyer and injuring several others.

The posts -- shared in court documents posted to the city's website Friday -- are similar to each other. One was sent in a private message on May 12 while the other was a public post shared four days later, according to court filings.

Both memes show a car driving through a crowd of people described as protesters. The public post carried the caption, "You have the right to protest, but I'm late for work."

The one shared privately was accompanied by a message from Fields that said, "When I see protesters blocking."

The prosecution said in its opening statement Thursday it would present the posts from May 2017 as evidence during the trial. They were shared publicly in court documents Friday, but haven't been presented to the jury.

Defense attorneys for Fields tried to stop the Instagram posts from being admitted into evidence, arguing they could unfairly prejudice the jury against Fields. But prosecutors said the posts were relevant and indicative of Fields' "intent, motive and state of mind," before he drove his car into counterprotesters on August 12, 2017.

An Instagram post made May 16, 2017, by James Fields, put into evidence by the prosecution at his trial.

The prosecution and defense agree Fields was behind the wheel of the car when it struck counterprotesters, his attorneys said Thursday, but they differ on his motivation.

Fields has been charged with first-degree murder in the death of Heyer, a local paralegal who attended the rally to speak out against white supremacy and racism. He also faces five counts of malicious wounding, three counts of aggravated malicious wounding and one count of failing to stop at an accident involving a death.

Heyer's loved ones have said she died for her beliefs. Her mother, Susan Bro, entered court Thursday morning and was embraced by a supporter as tears came to her eyes.

She sat in the front row of the courtroom behind prosecutors the entire day.

"I didn't think it would hit me as hard as it did," she told CNN when ask how she felt the first day went.

But Bro reiterated her dedication to showing up in court when asked whether it was too emotionally taxing for her to continue.

"Nope," she said. "I'm just committed to showing up every day."

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Witnesses recount moment after impact

Many of the case's details have already been revealed in the 15 months since the Charlottesville clashes.

Footage of the moment the car plowed into counterprotesters has been widely seen, and an independent review of the circumstances surrounding the events was released last December and blamed police for being unprepared and failing to protect the public. Many eyewitnesses have also spoken to the media.

Friday, the prosecution called more eyewitnesses, including several victims, to the stand.

One of them was Jeanne "Star" Peterson, who was in the crowd that day and struck by Fields' vehicle.

Peterson limped into the courtroom after she was introduced, and prosecuting attorney Nina Antony and a sheriff's deputy had to help her up to the witness stand.

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In the months since, Peterson has had multiple surgeries for the damage done to her leg. She plans to have her sixth sometime next year.

Peterson told the court the mood was joyful that afternoon as the crowd marched near 4th and Water Streets, because the Unite the Right rally had been stopped.

But that all changed when she was run over by Fields and saw Heyer thrown into the air.

"I remember seeing Heather in the air and remember her eyes," Peterson said. "I thought to myself, 'That's what someone's eyes look like when they're dead.'"

The state also called witness Tay Washington. She was driving a Toyota Camry that was struck by Fields' vehicle from behind, and told the court she'd seen him backing his car up and assumed he was trying to get out of traffic.

Washington had never seen a rally before.

"I've never seen so many white people standing up for black people." Washington said.

People fly into the air as Fields' car drives into a group of protesters in Charlottesville on August 12, 2017. The photo, taken by Ryan Kelly of The Daily Progress newspaper, won Kelly a Pulitzer Prize.

Ryan Kelly, a former photojournalist from The Daily Progress newspaper, also testified Friday. He won a Pulitzer Prize for his indelible photograph of the crash on his last day on the job.

Like other witnesses, he said he saw the Dodge Challenger backing up the hill, and believed it was trying to "get out of the way," he told the court.

Then he heard tires screeching, and the car sped past him.

"I saw the car accelerate the whole way into the protesters," Kelly said. He watched as it reversed and drove away.

Prosecutors went through more than 70 pictures taken by Kelly, who testified that he never saw Fields slow down and never saw any brake lights.

Fields also faces federal hate crime charges

The trial got underway Thursday after 16 jurors -- nine women and 7 men, one of whom is black -- were seated.

The defense has said Fields acted in self-defense , and on Thursday his attorneys tried to paint a picture of a hostile environment in which Fields might have felt threatened. They claimed their client saw a counterprotester with a gun in his hands, and said that Fields told police "he was scared to death."

Prosecutors, meanwhile, worked to establish a distinction between the hostile mood in the morning during the rally and the mood later in the day, when police ended the Unite the Right rally. The first witnesses called by the prosecution said the crowd in the afternoon was celebratory and the scene was peaceful.

Fields is separately charged with hate crimes in a 30-count federal indictment.

The prosecution in that case has alleged in court documents that Fields -- who they say espoused white supremacist ideals and denounced minorities on social media -- drove the car into the crowd with the intention of hurting people he targeted based on his bigoted views.

Fields has pleaded not guilty to the federal charges. It's unclear whether he has entered a plea to the state charges, though a trial would not likely be necessary if he had pleaded guilty.