Former Aston Villa star Dalian Atkinson threatened to kill his father in a "manic state" shortly before he was Tasered by police, his family said.
The footballer's final words were "I am the Messiah" as he was repeatedly shot with a stun gun by officers, according to relatives.
Moments afterwards he was knocked unconscious by a third Taser shot and died 90 minutes later after suffering a cardiac arrest.
Mr Atkinson's brother, Kenroy, 53, told The Sun the ex-Premier League star was "not in his right mind" on the night of his death.
"My brother had lost it," he said. "He was in a manic state and depressed - out of his mind and ranting."
He said Atkinson had tried to attack their 85-year-old father, Ernest, while visiting the family home on Telford in the early hours of Monday morning.
He said that the retired footballer, who had been undergoing dialysis for kidney failure, had also ripped out a tube in his shoulder and was "covered in blood".
Neighbours woken by the commotion called police, who apparently Tasered Atkinson three times as they tried to fell him.
Atkinson cried out "I am the Messiah" after a second shot failed to bring him down, his father told the newspaper.
The elderly widower said that he had been unable to sleep since his son's death as the family reels from the shock.
"We are all devastated," added Atkinson's brother Kenroy.
"Our family is heartbroken."
Relatives had yesterday indicated that Atkinson was suffering from a number of health issues including a weak heart.
His nephew, Fabian Atkinson, yesterday suggested officers would not have used the stun gun if they had known the ex-striker's medical history.
There have been numerous tributes from the footballing world to Mr Atkinson, who was a top-flight striker for Aston Villa in the 1990s.
The club today announced it would hold a minute's applause at their upcoming match against Huddersfield to honour him.
His ex-manager Ron Atkinson said the footballer "always had a smile on his face" in a personal tribute.
"He was a happy sort of guy, always smiling and very popular with his team mates."
However former friend and team-mate, Carlton Palmer, said Atkinson had struggled after his sporting career ended.
"I know Dalian found it difficult," he said.
"When you finish as a footballer, all of a sudden at 34 or 35 you have no routine and no structure to your life, and that can be a major problem.
"It can be a very dangerous spiral and unfortunately that's what it was for Dalian."
Mr Atkinson's death is now under investigation by the police watchdog Independent Police Complaints Commission (IPCC).
It comes after ex-soldier Spencer Beynon, who died after being Tasered by police in Llanelli, South Wales, in June after stabbing a dog and then himself.
Campaigners have raised concerns about the safety of the stun guns and called for restrictions on their use until more is known about the risks.