State Police say that 35 year-old Pamela McCarthy had a history of using the drug bath salts.
Investigators believe she was under the influence while she was assaulting her three year old child in the Madison County village of Munnsville on Tuesday night.
She later fought with neighbors, attempted to choke her dog and tried to bite a state trooper. Heather Ames witnessed the incident and said the trooper gave her plenty of warning that she would be tased if she didn't cooperate.
"The police officer warned her 5 or 6 times, I'm going to tase you. You need to let the dog go. You need to calm down - we can put handcuffs on you - she still didn't cooperate," said Ames.
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State police say trooper Christopher Budlong used the taser as a last resort when other attempts to get Pamela McCarthy under control didn't work.
The trooper had also used pepper spray on McCarthy but it had no effect.
"When an individual is under these bath salts - they are not responsive to any commands, any type of pressure points are ineffective," said Major Rodney Campbell with the New York State Police.
Pamela McCarthy went into cardiac arrest shortly after she was tased. An autopsy conducted on Wednesday was inconclusive. Neighbors say she had recently undergone heart surgery. The bath salts drug is also known to make a users heart rate speed up dramatically.
"We're unsure what caused her death at this point," said Campbell. "We're waiting on the toxicology results which should be back in a couple weeks but it's an unfortunate set of circumstances."