It remains to be seen whether murder charges hold up against the two young men arrested in the slaying of Eve Carson, but by all indications the Chapel Hill Police Department deserves a lot of credit for its performance in the case.The murder of UNC's student body president stunned the university, horrified the community and reverberated across the nation. The killing put the Chapel Hill police under enormous pressure, and Chief Brian Curran's department responded with calm efficiency and professionalism. Curran is new to his job; although he's been with the department for more than 20 years, he's been the chief for less than six months. But his composed response reassured a shocked community, and his department conducted what appears to have been a capable and thorough investigation.The police engaged the public in the quest, releasing security camera photographs of the suspects and sorting through hundreds of resulting tips. They kept the press and the public informed of the progress of the case, to the extent that they could do that without jeopardizing the investigation.Most importantly, they sought assistance and established cooperative collaboration with other law-enforcement agencies, particularly the Durham police. That collaboration bore the ultimate fruit when Durham officers made the arrests -- the first at 5 a.m. Wednesday, one week to the hour after Carson's body was discovered, the second about 24 hours later.The Durham connection also yielded a startling development: One of the accused, 17-year-old Laurence Lovette, was charged in another slaying, the Jan. 18 murder of Duke graduate student Abhijit Mahato.Unfortunately, recent revelations have raised troubling questions about some other branches of the law enforcement system. Both suspects -- Lovette and 21-year-old Demario James Atwater -- were on probation when Carson was killed. Atwater was on probation last June when he was convicted in Granville County on a charge of possession of a firearm by a felon. That conviction should have triggered a prompt review to revoke his probation -- but the paperwork to launch that process wasn't begun until five months later, and the warrant wasn't actually served until late February.That inexplicable delay was apparently exacerbated by a clerical mix-up. Atwater finally went to court for the probation violation hearing on March 3 -- but his case was assigned to the wrong courtroom, and so had to be rescheduled for later this month. Two days later Eve Carson was shot to death. The state and Wake County have begun investigations to determine what happened. Robert Lee Guy, the head of the state's probation system, has been candid about what appears to have been a breakdown in the system. He swiftly ordered an internal investigation because, he said, "There's no hiding this. We have not done quality supervision of Mr. Atwater."Meanwhile, as the authorities work to untangle the chain of events and as the legal process proceeds, another process, wider and deeper, continues. Eve Carson's family, friends, colleagues and the community at large continue to grieve, to remember and help each other begin the long process of healing what one resident called "our shattered hearts."