Fresh concerns have been raised over the safety of Tasers following the death of an ice cream man who was stunned while being restrained by police.
Friends and neighbours in Gorton, Manchester, disputed claims that Jordan Begley, 23, had been wielding a knife shortly before he collapsed and suffered a "medical episode" following a domestic dispute.
An Independent Police Complaints Commission (IPCC) investigation will now examine whether the use of the Taser was appropriate.
Locals described how police were engaged in a tense stand-off with the man, who lived with his mother and who had just finished a shift at an ice cream factory.
His employer Peter Sivori, 77, said he witnessed the attempted arrest but was ordered to move on by police when he offered to negotiate. "He was first class, he was a good worker, a bit quietish but he was hard working," he said.
Greater Manchester Police said it was unclear what had happened after officers arrived at the address around 8.15pm on Wednesday. Mr Begley was treated by paramedics at the scene but died later in hospital.
He is the seventh person to die after being shot with a Taser since they were introduced in Britain in 2003. Three months ago a man in Plymouth, who was doused in a flammable liquid, died when he burst into flames after being stunned by officers.
Yet while none of the five previous deaths in the UK has been confirmed as caused by the device, in the United States Tasers are believed to have contributed to more than 60 fatalities, according to Amnesty International.
Sophie Khan, an advocate solicitor who specialises in Taser-related injuries, said the devices were legally classified as firearms and were not simply for officer protection. She said they should only be deployed in life-threatening situations.
"We are going to see a massive increase in the use of Tasers when the latest figures are published in September. But there are no statistics to show that police are now in more danger. We ask where is the evidence? It is a hypothetical scenario they are creating which does not exist," she said.
Campaigners called for tougher rules governing their use and say officers - who undergo a three day course before being issued with a Taser - should receive more stringent training.
The Metropolitan Police is increasing the number of officers it issues with Tasers from 800 to 1,300 raising concerns that the devices are leading to a routine arming of police. The Police Federation, which represents rank and file, wants all front line officers issued with the weapons which incapacitate a target's neuro-muscular system.
Home Office figures to 2010 show that police have fired 2,185 times first since being armed with Tasers although their use rose by 66 per cent in the following year.
Deborah Coles, co-director of the death in custody charity Inquest said: "This latest death raises serious questions about the safety of Tasers that warrants proper scrutiny given their increasing use by police as a so-called 'non-lethal' use of force."
The Crown Prosecution Service is considering an incident earlier this year when a 63-year-old blind man was stunned in Chorley, Lancashire by officers searching for a suspect allegedly armed with a Samurai sword.
Deputy Chief Constable of West Mercia Police, Simon Chesterman, who represents the Association of Chief Police Officers on firearms issues, said that Tasers were "not risk free" but that the chance of harm was "very low" and normally the result of falling whilst incapacitated.
"There has been a significant increase in the use of Tasers but that runs parallel to the increase in the number of officers carrying them," he said.Reuse content