Police suspected that an infamous Miami man was under the influence of “bath salts,” but a medical examination today revealed that the zombie-like killer had only traces of marijuana in his system. The 31-year-old man was shot to death by police after attempting to eat a homeless man’s face for 18 minutes. Police wondered whether or not the man’s bizarre criminal behavior was the result of drug use, but his system didn’t show “any signs of other street drugs, alcohol or prescription drugs, or any adulterants found in street drugs,” a Miami medical examiner said.

Last month, the 31-year-old man successfully chewed most of the homeless man’s face off, including one of his eyeballs. The crime was committed on the side of the road during the daytime, but police are still not sure what motivated the man to commit it. The police department is currently seeking the assistance of outside forensic toxicology labs to determine if the man was under the influence of synthetic marijuana or LSD.