The secret hangman

"Peter Diamone, the Bath detective, is having women trouble. His boss wants him to find a missing person, the daughter of one of her friends in the choir. Murder becomes a possibility when a woman's body is found hanging from a playground swing."@en
"Inspector Peter Diamond, pursuing a serial killer who hangs his victims in public places around the city of Bath, must unravel motive and means before the secret hangman strikes again."
"Peter Diamond, the Bath detective, is having woman trouble. His boss wants him to find a missing person, the daughter of one of her friends in the choir. Another woman, who calls herself his Secret Admirer, wants to set up a meeting in a local pub. Then there is sexy Ingeborg Smith, the ex-journo detective constable, distracting the murder squad from their duties. Murder becomes a possibility when a woman's body is found hanging from a playground swing in Sydney Gardens and a suspicious second ligature mark is found around her neck. Diamond investigates the victim's colourful past. More hangings are discovered and soon he is certain that a secret hangman is at work in the city."