Atkinson, who was 48, died after police Tasered him near his father's home in Telford, Shropshire in the early hours of August 15, 2016. Witness reports said Atkinson shouted: "It's not working," when the police struck the first Taser, allegedly two more rounds were fired, each one administering a 50,000-volt shock.
He died of a cardiac arrest about 90 minutes after the incident. Earlier this year Home Secretary Amber Rudd agreed to allow the police to have more powerful X2 Tasers.
Atkinson was a star striker in the 1990s, most notably with Aston Villa, for whom he scored the Goal of the Season in the first year of the Premier League. He also scored to win the League Cup Final against Manchester United in 1994. Atkinson also played in Spain, Turkey, Saudi Arabia and South Korea before hanging up his boots in 2001.
At the time of his death relatives said he suffered from a bad heart and also had some mental health problems. The police officer who Tasered him was not wearing a body camera.
The IPCC issued a statement this week which said their investigative inquiries had concluded and a final investigation report was being compiled.
"Three West Mercia Police officers have been interviewed under criminal caution and were earlier served with gross misconduct notices," said the IPCC.
"IPCC investigators have spoken to around 15 other police officers as witnesses. Accounts have also been gained from more than 15 members of the public who witnessed events, as well as paramedics. A number of forensic experts have been consulted," they added.
"Analysis of a Taser deployed during the incident has been carried out. While all investigative actions have been completed, the IPCC investigation report cannot be finalized until the full pathology and toxicology reports are provided," said the IPCC.
On this day in one year ago, Villa hero Dalian Atkinson tragically lost his life. We will never forget him, Rest In Peace 🌹 pic.twitter.com/73aC2S2WL1— thevillazone (@thevillazone) August 15, 2017
"At the conclusion of our independent investigation I will consider whether to refer our investigation report to the Crown Prosecution Service to make a decision on any potential charges against police officers," said IPCC Commissioner, Derrick Campbell.
"A criminal investigation does not mean that criminal charges will necessarily follow," he warned.
"The report will also consider whether any officers should, in the view of the IPCC, face misconduct proceedings. We will share our finished report with HM Coroner, Atkinson's family and West Mercia Police," said Mr. Campbell.
Atkinson's family issued a statement this week:
"A year has gone by and we're still reeling from our loss. Dalian was our baby brother. Our determination to get to the facts and to see that appropriate action is taken will not be weakened by the passing of time. We're buckled in for the long haul," they said.
Amnesty International issued a report in 2015 designed to curb the excessive use of Tasers and described the UK as becoming too heavily dependent their use.
In 2015 a Home Office report found Afro-Caribbean people were three times more likely to be Tasered in Britain than white or Asian people.