The investigation into the circumstances around the death of ex-Sheffield Wednesday player Dalian Atkinson is continuing today.
The Independent Police Complaints Commission is looking into the death, which came after the retired footballer was tasered outside his father's house.
He is said to have made threats to his his father, Ernest, 85, during the disturbance.
Neighbours in Telford, Shropshire, said Atkinson was banging on his father's door demanding to be let in.
His dad said he was agitated and his brother described him as being 'not in his right mind' at the time.
An IPCC spokesman said: "A team of investigators from the IPCC have begun a thorough examination of the circumstances surrounding the death of Dalian Atkinson, 48, in Telford.
"His immediate family have been informed.
"West Mercia Police were called to a property at around 1.30am on Monday.
"Two police officers initially attended the address and whilst in contact with Mr Atkinson outside the property one of the officers discharged a Taser.
"Further police officers then arrived. Mr Atkinson became unwell and an ambulance was called. He was treated at the scene and taken to hospital where he was later pronounced dead.
"West Mercia Police referred the incident to the IPCC and the IPCC sent investigators to the scene and to oversee police post incident procedures.
"IPCC investigators have been conducting house to house enquiries in the immediate area and gathering available information. Police logs and radio transmissions are being obtained. The police officers involved and independent witnesses will be interviewed by IPCC investigators.
"Initial data from the Taser has been downloaded and it is being sent for further testing.
"A post mortem is due to be carried out later this week.
"None of the relevant officers were wearing body worn video cameras."
Rachel Cerfontyne, deputy chairman of the IPCC, said: “I would like to assure people that we have begun a full and thorough investigation into police contact with Dalian Atkinson prior to his death, including the level and type of force used.
"Our investigation team have been securing and preserving relevant evidence, and identifying witnesses. Investigators have met Mr Atkinson’s immediate family to explain our role and we have appointed a family liaison manager to keep them updated.
"My thoughts are with Mr Atkinson’s family and friends, and all those affected, at this difficult time.”