BORING, Oregon - July 9, 2010 - An autopsy on an 87-year-old woman tasered by deputies after they said she was threatening them with a gun showed she suffered from heart disease.

Dr. Larry Lewman of the medical examiner's office said Friday that Phyllis Owens had a history of heart disease, and a healthy person wouldn't have died in similar circumstances. He said he has yet to determine what effect the stun gun had on the woman's pacemaker.

The Clackamas County sheriff's office said Owens had a gun and was threatening a man working on a water line nearby at around 2:30 p.m. Thursday. When deputies arrived at the mobile home park on SE Leewood Lane, they said she threatened them with a gun, so they used tasers to subdue her.

After Owens was tasered, deputies said she became unconscious and unresponsive, and they began to provide CPR. She was taken to the hospital by ambulance, where she died about an hour later.

Detective Jim Strovink said the woman was recently released from the hospital, and pre-existing medical problems may have contributed to her death. Strovink said the woman might have also been suffering from dementia, he told the Associated Press.

The deputies involved in the incident will be placed on administrative leave during the investigation, which was being assisted in part by the Inter-Agency Major Crimes team at the request of the sheriff's office.

"Administrative leave affords those involved an opportunity to decompress with the enormous emotional entanglement generated, but also affords administrators and investigators immediate access to those individual employees," Strovink said.