After serving more than a year behind bars in New Jersey for assaulting a former girlfriend, David Goodell was transferred in 2010 to a sprawling halfway house in Newark. One night, Mr. Goodell escaped, but no one in authority paid much notice. He headed straight for the suburbs, for another young woman who had spurned him, and he killed her, the police said. The state sent Rafael Miranda, incarcerated on drug and weapons charges, to a similar halfway house, and he also escaped. He was finally arrested in 2010 after four months at large, when, prosecutors said, he shot a...