Mr. Mills, a reporter who is also by indirection a commentator (The Panic in Needle Park-1966) notices everything, wastes no words, and has invested this procedural account of the chief of homicide of the Queens County DA's office with the kind of urgency that is hard to escape. James Mosley by name, a careful, unimposing, reserved prosecutor is only willing to bring a case to trial when he has positive proof--thus the long delay on the Alice Crimmins case (that woman of many passionate but no maternal feelings who was convicted of killing one of her two children)--the first of the two stakeouts here. But the major part of the book deals with the hit of Ernie Rupoli, found ""like a skeleton with some stuff on it""; Ernie had obviously been killed by a co-Mafia member (earlier he had incriminated Vito Genovese of Murder, Inc; still earlier he had lost an eye to a bullet); and this is Mosley's long trial with not one legitimate citizen as a witness and all of them potential casualties. But ""to win a conviction in a Mafia murder case, a prosecutor must be assisted by a miracle or two."" There were no miracles...Mr. Mills' profile of the prosecutor on and off duty is immobilizing reading with the clean, cold peremptory authority of a .38.