John McMahon is an American author primarily known for his crime and thriller novels, often featuring Detective P.T. Marsh. He was born and resides in Southern California with his family and several rescue animals. McMahon’s writing style is characterized by gritty realism and complex character development, drawing inspiration from classic detective fiction while exploring morally ambiguous situations.
McMahon has achieved significant recognition for his work, with his debut novel, The Good Detective, receiving high praise from The New York Times, who deemed it "pretty much perfect." He has received numerous awards and nominations, including finalist status for the Edgar Award and Thriller Award, solidifying his place within the crime fiction genre.


