It started with a frantic call for help: "Something wrong with this guy. We need an ambulance."
A neighbor found 37-year-old Glen Leyba in his apartment, trashing so violently, the paramedics couldn't get close.
Then a police officer, hoping to restrain him, fired her 50,000-volt stun gun four times.
"It's been awful thinking about what he went through," says his mother Connie Leyba.
While the coroner ruled Leyba died from a cocaine overdose, CBS News Correspondent Wyatt Andrews reports the family believes that can't be the whole story.
"The only thing we know for a fact is that he died immediately after the last Taser," says his sister Shelly Leyba.
In fact, at least 40 people have died after being hit with stun guns. James Borden was shocked three times and died while tussling with jailers in Indiana. David Glowczenki died in his New York neighborhood just after being stunned. So did William Lomax of Las Vegas.
"In none of these cases has the person died while being hit with the Taser," says Rick Smith, CEO of Taser International.
At Taser Headquarters, Smith says every one of the 40 people who died, died of something else and not the Taser. He adds that no coroner has ever listed the Taser as the sole cause of someone's death.
However, CBS News has found several cases, like James Borden, where the shock from a stun gun is listed as one of the causes.
"In the cases I've done, there's usually some underlying problem," says forensic pathologist Dr. William Anderson.
Anderson says for some people already agitated or on drugs - some of the people most likely to get hit with a Taser - the jolt can depress breathing and turn lethal.
"There may be a small group of people that once it's used, may develop difficulties that may result in death," says Anderson.
The company insists, after 100,000 uses, the Taser is safe, and police rely on that claim.
In Glen Leyba's case, the officer who responded said she used the Taser specifically because of her training - training that taught her there are no documented cases of injury or death due to the Taser.
"It was absolutely wrong," says Shelly Leyba. "Glen was in a medical emergency,"
But the Leyba family thinks all those shocks to Glen had to make a difference.
"After the last Taser it was reported in the police officers report (that) he immediately became unconscious, and he never moved again," says Shelly Leyba. "They are using it excessively and in any situation that doesn't warrant that use of force."
Of the 40 who died after being stunned, almost every one was already high on drugs or in an agitated state, which raises the question: Did the shock of a stun gun push some of these victims off the edge?
Part 1: Stun Gun Fatalities Rise
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