Relatives of Steve Slaughter, a 14-year-old who was shot to death, including his mother, Tiffanie Jones, right, on Nov. 13. (Michael Robinson Chavez/The Washington Post)

“FOR WHAT? For five dollars? For 25 cents? For a bag of chips?” So asked the mother of 14-year-old Steve Slaughter , who was fatally shot in January during a bungled street mugging in Southeast Washington. He was the District’s fifth homicide victim in what has turned out to be a particularly deadly year, and his mother’s anguished question — “For what?” — bears repeating as the District confronts the pernicious gun violence that afflicts cities throughout the United States.

So far in 2018, 147 people have died in the District as the result of homicide, up 43 percent from the same period last year. Most of the homicides were gun-related; at least a dozen of the victims were juveniles. “It’s a massacre in slow motion,” wrote The Post’s Paul Duggan in a powerful account of Steve’s slaying. The teen, a high school freshman with a love of football and hopes for college, was gunned down Jan. 14 — shot three times by a would-be robber — as he walked with two friends after getting snacks at a neighborhood 7-Eleven. They had about $20 among them.

After recovering the car used in the shooting, police arrested a man who they say admitted his involvement and named two other suspects, who remain on the streets because police lack the corroborating evidence needed for arrest. Anthony Deandre Allen, the 22-year-old in custody, had agreed to plead guilty to second-degree murder after reportedly admitting to being the driver (not the shooter), but at the last minute he backed out of a plea agreement with prosecutors.

Mr. Allen, now facing trial on a first-degree murder charge for which he could be sentenced to life in prison, has no criminal convictions as an adult but faced previous weapons charges. Ten days after a judge dismissed a gun charge against him on grounds that the Beretta semiautomatic pistol allegedly found on him was the result of an illegal search, he was arrested after police said they discovered him with a .40-caliber Glock semiautomatic with a high-capacity clip. That charge was also dropped, Mr. Duggan reported, after his attorney successfully argued that a city gun law, later struck down by a federal court, made it impossible for him to get a carry permit. Is there any wonder that D.C. Police Chief Peter Newsham thinks the criminal-justice system in the District doesn’t treat weapons charges seriously — and that criminals know it?

Also disturbing was the revelation that the night before Steve was killed, Prince George’s County police spotted the car used in the crime parked across the border and determined it had been stolen. They didn’t notify D.C. police but instead attached a GPS device to track it, so they could hopefully make an arrest if it crossed the border into Prince George’s.

Who knows what would have happened if the car had been impounded that night, and who knows what would have happened if a D.C. Superior Court judge had not released Mr. Allen back into the community? Factors feeding gun violence are complex, and there is no magical solution. It is critical, though, to keep searching for answers so that no other mother has to ask “For what?”