They say grand juries will indict a ham sandwich. So what happened in the case of the pickup truck and the protesters at the Wyatt?

In this still image from video provided by WLNE-TV, protesters blocking an entrance to the Donald W. Wyatt Detention Facility begin to move as a pickup truck approached on Aug. 14. (WLNE-TV via AP/File)AP

PROVIDENCE — Certainly, there was no lack of evidence.

Investigators say they had 75 pieces of video. And with widespread media coverage, people across the nation saw footage of the black pickup truck swerving toward protesters outside the Wyatt Detention Facility in Central Falls on Aug. 14.

In a sense, the world was watching as the protesters screamed, the truck halted before lurching forward, and then correctional officers began dousing protesters in pepper spray.

But in the end, the only audience that mattered was the 23 members of the grand jury who decided Wednesday that no criminal charges were warranted against Captain Thomas Woodworth, the Wyatt officer who appeared to drive his truck into the crowd on that summer night.

“The old adage is a grand jury would indict a ham sandwich,” said Philip Stinson, a criminal justice professor at Bowling Green State University, in Ohio. “It’s a completely one-sided affair, and if the prosecutor wants an indictment, they typically get an indictment.”

Grand jurors are not required to explain how they reach a decision, but Stinson and other legal experts say grand juries often give law enforcement professionals the benefit of the doubt — except in shocking cases involving grave injuries.

In this case, investigators presented the grand jury with evidence from more than 70 witnesses, along with medical records and the extensive video footage. Woodworth’s attorney advised him not to testify in the case, but said his client never intended to hurt anyone.

Stinson said grand juries “seem to put themselves in the shoes of those law enforcement officers” when considering whether to issue a true bill indictment, in part because those who serve on grand juries tend to trust the justice system. With cases that appear more straightforward – like a robbery or assault – indictments are more common, he said.

Prosecutors also have an outsized role in grand jury proceedings, and their view of the facts can shape their cases. Several individuals who appeared before the Woodworth grand jury complained that prosecutors asked more questions about the protesters than they did about the correctional officers.

“The prosecutor can present the grand jury with instructions on the law that are heavily defense-oriented,” said R. Michael Cassidy, a Boston College Law School professor who previously served as a criminal bureau chief in the Massachusetts Attorney General’s Office. “There are all sorts of subtle ways that prosecutors can send signals to a grand jury — with a wink and a nod indicating the prosecutor doesn’t really want an indictment.”

Because grand jury proceedings are secret, and prosecutors are not in the room during deliberations, Cassidy said it’s difficult to determine how jurors reach their decisions.

While Woodworth’s case did not involve use-of-force in the line of duty, Cassidy said research shows grand juries are reluctant to indict law enforcement officers accused of assault “unless it is really egregious and there are serious injuries.”

“Those cases are tough when no one is hurt or no one is severely injured,” he said. “The more severe the injuries, the more the grand jury feels someone should be held accountable.”

Jeffrey Pine, who served as Rhode Island attorney general between 1993 and 1999, said it’s true that prosecutors can have an influence over grand juries, but he noted that jurors have the ability to subpoena records and call in as many witnesses as they want.

In the case of a Providence County grand jury, jurors sit for six weeks at a time. Unlike trials, prosecutors don’t have the same ability to strike jurors from a case in attempt to achieve a more favorable audience.

And while Pine acknowledged that it’s “technically true” that it can be easy to win an indictment, “someday you’re going to have to prove the case against the ham sandwich,” he said.

“Trial prosecutors don’t appreciate it if the person running the grand jury sends out a bunch of unprovable or weak cases,” Pine said.

Attorney General Peter F. Neronha said he believed the grand jury worked to “deal with complicated legal and factual issues, including determining the intent of those whose conduct was within the scope of their investigation.”

“Often, these are not easy issues for grand jurors or trial jurors to grapple with,” Neronha said.

But Cassidy said the larger context is that in years past, prosecutors tended to review police reports and make their own determinations about whether a law enforcement officer should be charged. And those prosecutors often found the officers’ actions justifiable, he said.

Now, prosecutors are more likely to bring these types of cases to grand juries, Cassidy said.

“In the last 10 years and with Black Lives Matter, prosecutors understand the importance of presenting cases to the conscience of the community — the grand jury,” he said. “But that doesn’t mean the grand juries always indict.”

Grand jurors might side with the police, reasoning that police officers have difficult jobs, and disbelieve other witnesses, he said.

So while it’s a good trend that grand juries are being given responsibility for these types of cases, Cassidy said, “Whether grand juries treat civilian targets and law enforcement targets the same — I don’t know if we are there yet.”