WASHINGTON (Reuters) - More than 1,000 people in the U.S. have died after police stunned them with Tasers, and the stun gun was ruled to be a cause or contributing factor in 153 of those deaths, a Reuters examination found.

In the most thorough accounting to date of fatal police encounters involving the paralyzing stun guns, Reuters found that nine in 10 of those who died were unarmed and one in four suffered from mental illness or neurological disorders. Taser International Inc, the stun gun’s manufacturer, said its weapons are almost never to blame when someone dies after being stunned. Taser this year changed its name to Axon Enterprise Inc AAXN.O.

Reuters collected autopsy results for 712 of the more than 1,000 deaths it documented in police incidents where Tasers were used. Nearly all those deaths occurred since 2000, when Tasers began gaining popularity with U.S. police. A majority of the deaths involved other types of force such as batons or pepper spray.

This story is the first in a series, “Shock Tactics,” about the weapon that transformed American policing. To read the story, click on or go to here