No Coffin for the Corpse by Clayton Rawson

Do you believe in ghosts? Dudley Wolff did. He was a self-made man and head of Wolff industries which made the explosive powders for bombs and other materials necessary for the war. Young reporter Ross Harte had written an unfavorable story about Wolff which made Wolff very, very angry. The trouble for Ross Harte was that he was in love with Wolff's daughter Kathryn, and Wolff refused to let Ross anywhere near her. Wolff had bought the paper for which Ross worked and fired the young man.

Wolff supported two researchers because of his great and overwhelming fear of death. Dr. Sydney Haggard was doing scientific research into longevity, Francis Galt was doing research on the supernatural. They were both present on the night when Dudley Wolff received a visit from the very mysterious Mr. Smith.

Mr. Smith was sitting at the desk in Wolff's office, and later, nobody seemed to know how he got into the house. Mr. Smith was thin with dark eyes and a mustache and a close cropped beard. He had come to blackmail Wolff with photocopies of checks which Smith was sure that Wolff would not want the Senate's munitions committee to see. He was asking one hundred thousand dollars for these checks. Wolff grew very angry at this blackmail attempt and struck Smith. The chair with Smith went over backwards and Smith struck his head. Dr. Haggard was called to the study and said that Smith was dead. Dr. Haggard wanted to call the police but Anne Wolff, Dudley's wife, stopped him, and Dudley threatened to cut off his funding and take away his laboratory. Dr. Haggard gave in. Wolff, Haggard, and Albert Dunning, Wolff's secretary, took the body to a private graveyard close by and buried it.

The Great Merlini, magician extraordinaire, was preparing to put on a show, The Hocus Pocus review. Ross Harte, hoping to get a job went to see him, and found, to his amazement the Kathryn Wolff was also working for Merlini. She appealed to Merlini to come and help her father because he was seeing a ghost and was deathly afraid of it.

Merlini and Ross Harte did go to the Wolff home, and found that Wolff was seeing a ghost which bore a striking resemblance to the man which Wolff had murdered. This was followed by the murder of Dudley Wolff in what appeared to be a locked room. Merlini and the police investigate, the dead man seems to appear again and dies again which was confusing because he had also died several years before the book began.

Merlini explained how all the murders were committed, and a lot of the explanation depended on methods used by professional magicians and mediums. (Spoiler alert) Part of the method of committing one of the murders depended  on a technology which 21st century readers may not know about but which was used in the 1930's.

Clayton Rawson was a professional magician, an editor of Ellery Queen's Mystery Magazine, and was one of the founders of The Mystery Writers of America. He wrote four Great Merlini mysteries. This book is the last and was published in 1942. His books have been reissued as e-books by Mysterious Press.