The Independent Police Complaints Commission’s investigation into the death of the former Aston Villa player is nearly complete and it is putting together a final report.
But the IPCC says the criminal investigation does not necessarily mean criminal charges will follow.
The former Aston Villa player died aged 48 after being shot by a police Taser outside his father's house in Meadow Close, Trench, Telford, on August 15 last year.
The retired footballer became unresponsive and died despite the efforts of hospital doctorswho battled for 35 minutes to try to save him.
The three West Mercia Police officers were earlier served with gross misconduct notices.
IPCC investigators say they have have spoken to around 15 other police officers as witnesses as well as 15 members of the public and paramedics. A number of forensic experts have also been consulted.
Investigators have transcribed relevant police radio transmissions and examined police policies on the use of force.
Analysis of the Taser which was deployed on Mr Atkinson has been carried out.
While all investigative actions have been completed, the IPCC investigation report cannot be finalised until the full pathology and toxicology reports are provided.
IPCC Commissioner, Derrick Campbell, said: “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.
"A criminal investigation does not mean that criminal charges will necessarily follow.
“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, Mr Atkinson’s family and West Mercia Police.
"We have been keeping the interested parties as informed as we can throughout our enquiries. I am grateful for the patience shown by all concerned during the course of this rightly thorough investigation.”
In September nearly 200 people joined the 'Justice 4 Dalian Atkinson' in Telford Town park march.
Assistant Chief Constable Martin Evans said: "Our thoughts and sympathies are with the family and friends of Dalian Atkinson.
"We continue to cooperate with the Independent Police Complaints Commission throughout their independent investigation. It would not be appropriate for us to comment further at this time while that investigation is ongoing."