Erle Stanley Gardner

First published in the US in 1946, ''The Case of the Backward Mule'' features protagonist Terry Clane, an expert in Eastern ways who returns to San Francisco and gets tangled in a murder, an escaped convict, and a blood-stained statuette of a Chinese philosopher riding a mule backward. Terry Clane is just back from China. Clane once gave to his former fiancée, Cynthia, a small statue of Chow Koh Koh riding a mule backwards.
The police reveal the statue is now stained with the blood of a murder victim. Cynthia's new fiancé Harold escapes death row, a murder takes place, and Clane uses mental concentration learned abroad to fool a police lie detector. Believing Harold is innocent, Clane navigates a dangerous game of hide-and-seek throughout San Francisco's Chinatown to protect Cynthia and find the real killer.