Dana Mulhauser was a trial attorney at the Civil Rights Division of the U.S. Justice Department from 2007 to 2019. She is the founding chief of the Conviction and Incident Review Unit at the St. Louis County (Mo.) Prosecuting Attorney’s Office.

This article has been updated.

Sometimes, horrific violence doesn’t get prosecuted because there’s a bad prosecutor. Sometimes, horrific violence doesn’t get prosecuted because there’s bad law. Sometimes, it’s both.

And while replacing a bad prosecutor is important, replacing a bad law is even more so.

Two days ago, a graphic video began circulating online of a vicious killing in southern Georgia, where two white men confronted an unarmed black man, Ahmaud Arbery. The pursuers, Gregory McMichael and Travis McMichael, claimed afterward that the 25-year-old Arbery resembled a man suspected in break-ins of unoccupied homes in the neighborhood. Arbery’s family says he was out jogging.

The McMichaels — a father and son — told police that when they saw Arbery running, they grabbed a .357 Magnum and a shotgun, jumped into their pickup and chased him. They attempted to block Arbery in by parking their truck in the road.

It is at this point that the newly surfaced video, filmed by another driver, begins. It shows Arbery running down the street, then trying to go around the McMichaels’ truck. 64-year-old Gregory McMichael is standing in the truck bed, .357 Magnum in hand.

The video briefly cuts sideways; when it cuts back, Arbery and Travis McMichael are seen wrestling over McMichael’s shotgun. Travis McMichael, 34, shoots Arbery three times, killing him.

The scene evokes the killing of Trayvon Martin in 2012, during which George Zimmerman, a member of a neighborhood watch group, pursued the teenaged Martin after seeing him walk around the neighborhood in a way that he deemed “suspicious.”

It also evokes centuries of lynch mobs, in which groups of white men brutally murdered black men. Georgia alone had 594 lynchings between 1877 and 1950.

On Thursday night, both Gregory and Travis McMichael were arrested and charged with murder. It took two months, a leaked video and a public outcry for that to happen — and it’s possible the two men may never be convicted. There are two reasons.

One concerns the prosecutors. The first prosecutor assigned to the case recused herself — rightly and quickly — after realizing that Gregory McMichael was a former employee of her office. Her successor, George E. Barnhill, spent more than a month in charge of the case before recusing himself because of his own conflict of interest, a lesser one — Barnhill’s son works in the prosecutor’s office where Gregory McMichael used to work, but Barnhill says the two did not overlap.

But then Barnhill released a three-page letter, explaining why he did not believe that the McMichaels should be prosecuted. The letter is impassioned, opinionated and entirely improper.

The point of recusal is the acknowledgement of bias or the appearance of bias. For a prosecutor to offer, after recusal, an opinion on the case, relying on evidence in their possession but not available to the public, serves only to poison a potential jury pool and influence successor prosecutors.

The more serious issue is with the law itself. Barnhill says the men were acting under Georgia’s citizen’s arrest law, which allows a “private person” to make an arrest “if the offense is committed in his presence or within his immediate knowledge.”

There is much that we, as members of the public, don’t know about this particular citizen’s arrest. We have seen no evidence that the McMichaels had “immediate knowledge” that Arbery had committed a felony, which is a higher standard than the “probable cause” required for police to make an arrest. It could, instead, be that, as happens all too commonly, they saw one black man and confused him with another.

That is exactly the reason the state of Georgia should not allow private citizens to play amateur detective with guns in their hands. The decisions are too difficult, and the consequences are too dangerous.

Police — actual police — go through intensive training on use of force before being equipped with a gun. A typical police academy spends 40 classroom hours on use of force and defensive tactics, plus more time in hands-on drills and practice scenarios.

Prospective officers also get trained on probable cause: what is enough evidence to initiate an arrest, and what is not.

Even after all of that, officers sometimes use force when they shouldn’t. Those are the cases that I’ve spent most of the last decade prosecuting.

If even trained, seasoned officers sometimes make criminally wrong decisions, what can we expect of private citizens who have received none of that training?

It is not fair to the citizens of Georgia to give them the right to play policemen but none of the training. We no longer live in the Wild West, in which law enforcement often had to be left to private citizens. Our laws should leave the 19th century and join us here in the 21st.

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