not quite the whole story.
http://www.huffingtonpost.com/2012/06/27/rudy-eugene-face-marijuana-medical-examiner-results_n_1632253.html
The statement did not address previously reported autopsy findings of what appeared to be undigested pills in Eugene’s stomach, and an expert told the Associate Press marijuana alone was not likely to cause such an attack:

“The problem today is that there is an almost an infinite number of chemical substances out there that can trigger unusual behavior,” said Dr. Bruce Goldberger, Professor and Director of Toxicology at the University of Florida.
Goldberger said that the medical examiner’s office in Miami is known for doing thorough work and that he’s confident they and the independent lab covered as much ground as possible. But it’s nearly impossible for toxicology testing to keep pace with new formulations of synthetic drugs.

“…The challenge today for the toxicology lab is to stay on top of these new chemicals and develop methodologies for them, but it’s very difficult and very expensive.” Goldberger said. “There is no one test or combination of tests that can detect every possible substance out there.”