BERSERK By Graham Chester (True Crime, $255) THE motiveless random massacre is a crime of the 20th century, says Mr Chester in his introduction to this catalogue of pointless slayings. Most occur in the US, which comes as no surprise. The cases Mr Chester examines include that of James Hubert who shot dead 21 people in a Californian McDonald's in 1984, and Michael Ryan who gunned down 16 passers-by in the quiet English town of Hungerford in 1987. In each case the author relates the crime itself, the protagonist's background and the aftermath for victims, their relatives and friends. Comparisons are kept to a minimum, but a definite character pattern of quiet loners, with a big interest in weaponry emerges. DEADLY DOCTORS By Max Marquis (Warner Books, $85) FIVE true stories set in and around the turn of the century about British medics who turned to murder, usually doing away with their wife, maid or prostitute. Methods ranged from cold, clinical poisoning to the distinctly unscientific such as bludgeoning to death. Historically, the book has some merit - murder was certainly easier to get away with in those days - but the stories are told in such a naive and patronising manner they are rendered dull. DAD, HELP ME PLEASE By Christopher Berry-Dee with Robin Odell (True Crime, $85) IN November, 1952, Christopher Craig shot dead PC Sidney Miles during a robbery attempt. At 16, Craig was too young to hang for the crime, but his accomplice and friend DerekBentley - an epileptic with an IQ of 66, wasn't - and did. This book, on which the movie Let Him Have It was based, is a tragic and compelling account of how such a ridiculously far-fetched instance of ''an eye for an eye'' could be allowed to happen in the name of justice. Despite his mental age, the jury's plea for mercy and a nationwide campaign to have the sentence commuted, Bentley still swung for a crime he didn't commit. HANGMAN By Brian Bailey (True Crime, $72) ''CAPITAL punishment achieved nothing except revenge,'' wrote Albert Pierrepoint, Britain's last state executioner, and the man who hanged Derek Bentley (see above) in 1953 and Ruth Ellis in 1955. Hangman is a grim chronicle of Pierrepoint and his predecessors in the job, stretching back three centuries. They include William Marwood, inventor of ''the long drop'' and notorious John Price who would himself hang one day. MURDER AND MAYHEM Introduced by James Ellroy (Arrow, $50) FROM Manson to Sutcliffe and Dahmer, this is a pocket guide to the world's most notorious killers. It's difficult to determine the purpose of the book, since it devotes only scant pages to each subject. There is no attempt to seek any reason for their horrific crimes, nor to add any background colour. POISONED BLOOD By Philip Ginsburg (Michael O'Mara, $255) MARIE Hilley, born in 1933 America, seemed an ordinary, if secretive, young woman until the day she carefully and deliberately poisoned her husband. She got away with that one and went on to attempt to kill her daughter and assorted friends and neighbours. She also built up a mine of secret identities and even faked a suicide to cover her trail. Mr Ginsburg's biography of this strange woman is revelatory at times, but over-burdened with irrelevant detail which seems to seek clues where there are none.