Brutal, senseless killings are a community tragedy. There is no way to reverse the loss, but when law enforcement responds swiftly and efficiently, that at least can be something of an antidote to people's grief, fear and anger.

The slaying last week of Eve Carson, student body president at UNC-Chapel Hill, elicited just such a response, which now has resulted in the arrest of two suspects. This took good, cooperative work by police departments in Chapel Hill and Durham. The arrests were prompt and no one was hurt. It will fall to the courts to determine whether the two young Durham men who were arrested -- both presumed innocent -- are in fact guilty as charged, but this is the path that must be followed for justice to be done.

Demario James Atwater, 21, was being held in the Orange County jail following his arrest in Durham early Wednesday in connection with Carson's death. The second suspect, Laurence Lovette, 17, was arrested in Durham yesterday. Unexpectedly, he also was charged in the January slaying of Duke University graduate student Abhijit Mahto and was being held by Durham authorities. (Police agencies have provided different spellings of Lovette's first and last name.) He is the second person arrested in the the Mahto case.

Police were helped significantly in the Carson case by the ubiquity these days of security cameras. Images were captured by cameras at an ATM machine and a convenience store, where two men tried to use Carson's bank card. Those images, promptly released, and an alert public may have made the difference in this investigation. Carson had been found shot to death at a Chapel Hill intersection about a mile from the university. It's possible that she was carjacked.

Still, the arrests do little to ease the crushing loss felt in Chapel Hill and on Duke's campus -- indeed, among all who knew and admired the slain students. The funeral for Carson, 22, was Sunday, in her home town of Athens, Ga., where she had excelled and won a top scholarship to UNC-CH. The university will hold a second memorial service for her when students return from spring break next week. The magnitude of the response to her death, both on campus and in Athens, is a testament to her life fully lived.

Similarly, here's how Duke Professor Tod Laursen, Mahto's adviser, described the 29-year-old computer engineering student, who was shot to death in an apparent robbery in his apartment: "He made friends very easily and always had a smile on his face. Our research team was particularly close to Abhijit."

Inevitably, the arrests raise questions about how young men who have broken the law are handled in the court system. Atwater was put on probation in Wake County in 2005 for stealing two guns in a house break-in. He was convicted in Granville County last year of possession of a gun by a felon. Yet he was still on the streets. A hearing to revoke his probation was set for March 31, but that is too long of a wait for crimes involving guns.

How many other people with a similar potential for violence are roaming free across the Triangle and elsewhere in North Carolina? Lovette's past is less clear, due to the different spellings of his name, but he also appears to have had a criminal record, involving lower-level offenses.

Wisely taking into account the hard upbringing of many who enter the justice system shouldn't translate into letting gun-wielding felons stalk neighborhoods (and not just African-Americans, who are disproportionately represented in crime statistics but are by no means alone). North Carolina courts need to reassess their policies to make sure that mercy and useful treatment programs are dispensed in the right amounts, but also to the right people.

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