Mr Smith was given emergency first aid, but died at the scene. A post-mortem examination has since been carried out ahead of a future inquest.
Investigators at the IOPC are now looking into the actions and decisions made by Avon and Somerset Police prior to Mr Smith’s death.
The watchdog’s director Derrick Campbell said his thoughts were with Mr Smith’s family and friends, as well as “everyone affected by this shocking and tragic incident”.
“We want to reassure everyone that we will independently investigate all the circumstances surrounding this incident, including the use of a Taser,” he added, explaining that initial accounts had been taken from the officer and ambulance staff involved.
