They must have missed him by a few minutes. Kellman says he stopped just down the street from his parents' house to pick up his gun from a stash beneath a piece of loose sidewalk. Then he walked up to Prospect Street to shoot his ex-girlfriend. The police have far less freedom in domestic violence cases than in other types of arrest. If the officer has reason to believe that a crime has been committed, he or she must make an arrest.
Some critics believe that it puts women at greater risk, serving only to further anger the batterer.
In the case of Smith and Kellman, the New Haven police followed procedure, arriving within minutes of the 911 calls and booking Kellman on each one. Violation of a protective order is a felony charge and would have carried a stiffer sanction than the repeated misdemeanors with which Kellman was charged. Maybe the stiffer charge would have frightened Kellman into calming down. Maybe it would have given Smith more confidence in the response of the police. Maybe it would have warned the police to keep closer watch on him.