Heart condition could have contributed to diver's death

A Minnehaha County diver who drowned during a July training exercise died from a lack of oxygen to the brain that could have been complicated by a heart condition, according to the county coroner.

A death certificate released Wednesday morning says Jeff Thumma's primary cause of death was "cerebral anoxia due to uncertain etiology while diving" and "atherosclerotic cardiovascular disease."

His death has been declared accidental.

Thumma, an experienced, volunteer diver, was taking part in a Minnehaha County dive team training July 10 at Family Park in western Sioux Falls. While underwater, Thumma tugged at a safety rope four times to signal an emergency.

It only took about two minutes for rescuers to pull Thumma from the water, but he was unresponsive and died after several days on life support.

Police spokesman Sam Clemens said Thumma's diving equipment fully functional at the time of the incident. Clemens said the gear was sent off Diving Technologies in Sunrise, Florida for an extensive expert analysis.

"We searched high and far to find out if there was something we could have prevented," Minnehaha County Emergency manager Lynn DeYoung said. "There was something that caused this, but no one knows exactly what happened."

It was the first time in the 40 years the Minnehaha County Dive team has been maintained that a diver has died. About three times a month, year-round, members of the dive team travel across the region for training.