Updated 09/28/11 – 4:23 p.m.

CHICAGO (CBS) — An autopsy on Wednesday proved inconclusive in the death of a 62-year-old Roselle man who died after he attempted to clear a nest of bees or hornets that was near his home.

As WBBM Newsradio’s Steve Miller reports, fatal attacks by bees are rare, but initial reports said Bruce Madiar, 62, died after just such an attack on Monday afternoon.

An autopsy performed on Wednesday was inconclusive, pending further studies, according to the Cook County Medical Examiner’s office. A spokeswoman said the initial autopsy did not reveal obvious signs of anaphylactic shock — a likely result of fatal bee stings — or a heart attack, so further studies were needed.

LISTEN: WBBM Newsradio’s Steve Miller reports

The medical examiner’s office said Madiar, of the 500 block of Dee Lane in Roselle, was trying to clean a beehive from his home Monday evening. The bees apparently became angry, and formed a swarm to attack him. He was pronounced dead at 6:21 p.m. at Alexian Brothers Medical Center in Elk Grove Village.

However, first responders said when they arrived they didn’t see bees or hornets – or stings on Madiar. But their superiors said their priority was treating Madiar because he was in cardiac arrest.

WBBM Newsradio has learned the medical examiner’s preliminary report says Madiar’s wife told investigators her husband’s face and tongue were swollen when he was taken to the hospital. Such symptoms can be indicative of an allergic reaction.

Rich Miller’s Capitol Fax reported Tuesday that Madiar was the father of Eric Madiar, the chief legal counsel and parliamentarian for the Illinois Senate Democrats.

The Sun-Times Media Wire contributed to this report.