Byline: Associated Press

Four men were arrested in the slaying of a rookie policeman shot three times in the head... while guarding the home of a man who had complained about drug dealing in his neighborhood, police said Friday.

Police Commissioner Benjamin Ward said investigators believe that the officer, 22-year-old Edward Byrne, was shot on orders from a jailed drug kingpin.

Two of the suspects were arrested late Thursday, a third surrendered with his mother Friday, and the fourth, who was in custody on other, unspecified charges, was arrested Friday evening, police said.