The Case of the Beheaded Gringo Pig -- a tortuous murder investigation clouded by enough suspects, black magic and nanacatl dreams to leave you reeling. After assembling for the start of an IACP convention in Guadalajara, the New York Commissioner of Police is found slain along with a naked Mexican girl in the cane fields of the nearby village of Zacapango. Lo and behold, the cop-killer might be a fellow officer -- either a trigger-happy ""nigger-hater,"" an Uncle Tom, or another who's on the take -- but then there's also the unscrupulous Mexican Host Chief, Colonel Guzman, and old Major General Robert Cawthorn (Ret.) whose incriminating diary might just supply the answer. Alas, the true villain seems to be an anthropologist-author zapped-out by his experiences with a legendary Nahuatl sorcerer and too many hallucinogens. Marlowe puts just about anything in the pot and lets it boil over.