Hanged man's house [1st ed. in the U.S.]

The head of a research establishment is found murdered. But there is an even bigger shock in store when another body is found mummified in his cellar.

What is the connection between them? Things certainly aren't what they seem, and Supt. Dunn must delve deep into the lives and personalities of those involved with the dead man before he can hope to find a solution.