Former ISU and Dallas Cowboys running back Ennis Haywood died primarily because of a mixed ingestion of ethanol and two drugs, the Tarrant County (Texas) Medical Examiner’s Office said Friday.

Bronchial asthma made a “significant” contribution, the office said in a release, but it was not the primary cause. The death was ruled accidental.

Haywood, a two-time All-Big 12 selection who ranks fifth on the ISU career rushing chart with 2,862 yards, died the afternoon of May 11 in Dallas after he began vomiting in his sleep about 18 hours before.

According to the autopsy report released Friday, Haywood’s death resulted from a mixture of ethanol, codeine and an unidentified benzodiazepine. Those substances can prove dangerous when taken in combination, experts said.

Codeine is commonly used medicinally as a narcotic, prescribed for the relief of moderate pain and cough suppression.

The benzodiazepine family of depressants is used to produce sedation, induce sleep, relieve anxiety and muscle spasms and to prevent seizures.

The drug is also sometimes used to treat asthma.

Because the drugs are prescribed tens of millions of times per year, they are usually not associated with drug abuse.

Ethanol is a component of many alcoholic beverages and can lead to short-term drunkenness and long-term toxic effects when taken in high dosages, Story County Medical Examiner Paul Gryte said.

Haywood’s blood-alcohol content, based on a sample taken about 12 hours after he was admitted to an Arlington, Texas hospital, was well below the legal limit for driving.

The autopsy report also highlighted congestion in microscopic sections of Haywood’s lungs.

An initial autopsy in Dallas the day after Haywood’s death yielded no conclusive results. Friday’s release came after the completion of toxicology tests done on Haywood’s blood and urine.

Haywood was 23 when he died and was entering his second season with the Dallas Cowboys after signing as an undrafted free agent following the 2002 NFL Draft. He spent the 2002 season on the Cowboys’ practice squad after leading them in rushing during the preseason.

This preseason, Haywood was expected to compete for a spot on the Cowboys’ 53-man regular season roster. He had no known serious health problems before his death — he completed a team physical one week before his death.

He was survived by his parents, Ennis Sr. and Carol, his high school sweetheart and wife, Kristal, 3-year-old daughter Ennicia and the family’s newest member, Haven Haywood — born June 19, five weeks after Ennis’ death.

During Iowa State’s 9—3 2000 season, which included the Cyclones’ only bowl victory in history, Haywood ran for 1,237 yards, the ninth highest single-season total in school history. He also earned first-team All-Big 12 honors for the first time.

Only Troy Davis has gained more yards per carry as a Cyclone than Haywood, averaging 5.6 yards per carry to Haywood’s 5.0.