Avon and Somerset Police is under investigation into what led officers to use a Taser on a vulnerable man with autism and learning difficulties.
The 26-year-old was Tasered in August last year before he was arrested and charged with assaulting a police officer and criminal damage.
But the charges after the incident in Bristol were later dropped by the CPS, and now the police watchdog is investigating whether the use of the Taster was "proportionate".
The investigation follows a complaint from the man's mother who alleges police failed to properly investigate, or provide appropriate support, for him despite his health problems.
The Independent Police Complaints Commission (IPCC) is also investigating how the force dealt with the same man on three separate occasions in 2014.
Two incidents saw the man convicted of burglary and harassment, while the CPS decided not to proceed with one charge of assault.
An inquiry by the IPCC into police conduct surrounding the murder of Bijan Ebrahimi has moved a step further, on the first anniversary of his death.
Mr Ebrahimi was beaten to death and then set on fire in Bristol last July, after being wrongly branded a paedophile.
The IPCC has sent a file of evidence to the Crown Prosecution Service, relating to the conduct of three officers and how they dealt with Mr Ebrahimi's repeated calls for help.
Police who shot a man in Keynsham have confirmed they were responding to a domestic incident involving a firearm.
The matter has been referred to the IPCC and the Force's Professional Standards Department.
A man in his 40s, who uses a wheelchair, was arrested on suspicion of firearms offences and remains in hospital in a stable condition.
Officers say they were threatened by a man with a firearm.
The injured man is under arrest and in a stable condition in hospital.
Complaints against police in Gloucestershire have risen by almost twenty percent in a year, it was revealed today,.There were 480 complaints between April 2010 and March 2011 but the figure went up 20 percent to 573 in the year April 2011 to March 2012.