A medical examiner has ruled that marijuana was the only drug in the system of the Florida man shot dead while "eating" another man's face.

The Miami-Dade County medical examiner released the results of toxicology tests on 31-year-old Rudy Eugene on Wednesday. The tests found marijuana in his system, but no other street drugs, alcohol or prescription drugs.

Eugene was shot dead by police as he chewed on Ronald Poppo's face beside a busy highway in full daylight. In the aftermath of the attack Eugene was widely reported to have ingested a drug known as "bath salts", spawning a wave of media interest in the substance.

However the lab tests appear to have rendered the hysteria redundant, after the medical examiner's department ruling out the most common components of bath salts. An outside forensic toxicology lab also confirmed the results.

"The department has ruled out the most common drugs found in 'bath salts'," a press release from the ME's office said.

"The laboratory has tested for but not detected any other street drugs, alcohol or prescription drugs, or any adulterants found in street drugs. This includes cocaine, LSD, amphetamines (ecstasy, meth and others), phencyclidine (PCP or "angel dust"), heroin, oxycodone, Xanax, synthetic marijuana ("spice"), and many other similar compounds."

The incident happened on 26 May when Eugene, who had a history of violence, stripped naked and ripped off some 80% of Poppo's face with his teeth.

CCTV footage showed Poppo, a 65-year-old homeless man, kicking his legs during the attack, suggesting he was conscious for at least part of the ordeal. Eugene was shot six times by police officers after ignoring orders to stop.

Poppo survived the attack, but had one eye gouged out and may be blind in the other, according to a WPTV report. He has undergone several surgeries and remains hospitalized.

After the attack there was much discussion of bath salts and the drugs effects, with reports that Miami police had linked bath salts to the attack, quoting experts who said Eugene was exhibiting "classic signs of someone high on the drug".

Armando Aguilar, president of the Miami Fraternal Order of Police, said there were similarities between the attack on Poppo and other cases involving bath salts, telling ABC News that users "suddenly have super human strength" and "become violent and they are burning up from the inside".

Bath salts, a synthetic drug made in a lab, described as "like cocaine, meth, and speed" in the way they "work by stimulating the central nervous system", according to Forbes.