Safer Dead by James Hadley Chase

James Hadley Chase is probably the best know synonym of René Lodge Brabazon Raymond, an English writer also known by other pen names, including James L. Docherty, Raymond Marshall, R. Raymond, and Ambrose Grant. He is one of the best known thriller writers of all time. He was influenced by American crime writes and writers of hardboiled pulp fiction, but he rarely visited the United States and the books are based on knowledge acquired by reading and using reference materials. He has written some 90 books, almost half of which have been made into movies. 

In "Safer Dead", Chet Sladen, a crime writer, is asked to investigate the cold trail of a showgirl who has disappeared fourteen months earlier. It seems hopeless, and the police have lost interest. But when questions are asked, things start to happen, witnesses are murdered and an attempt is made on Sladen’s life. The showgirl is dead encased in cement at the bottom of a lake, but this is part of a larger plot. Following clues that lead to numerous murders, Sladen will solve the case.