A skydiving instructor who was killed along with a student who was strapped to him when they landed in the ocean off Dillingham Airfield in January drowned, according to a newly released autopsy report by the city Department of the Medical Examiner.

But Dr. Gayle Suzuki, who signed the report, said she could not rule out the possibility that instructor Erich Mueller might have experienced a "cardiac arrhythmia" or irregular heartbeat during the jump "which caused him to become unconscious and land in the water which eventually led to his drowning."

Mueller and Saori Takahashi were near death after rescuers pulled the pair out of the water about 100 yards off shore Jan. 6. It was estimated that the two had been under water for up to 30 minutes.

Investigators determined there were no mechanical problems with the tandem parachute the two used during the jump.

Other skydivers who saw the jump from a plane said the parachute opened properly but that Mueller appeared to lose consciousness as the pair made what was supposed to be a final approach for a landing at the Waialua end of the airfield.

Instead, the parachute continued out across Farrington Highway and the two parachutists wound up in chest-deep waters.

Rescuers said the pair became entangled in the parachute's canopy and rigging lines, hampering rescue efforts.

Takahashi died of problems associated with near drowning and blunt force injuries to her head, neck, chest and lower extremities.

Tests for alcohol and drugs were negative for both victims, according to the autopsy.

Reach David Waite at dwaite@honoluluadvertiser.com.