Police were called to the home of 32-year-old Andrew Pimlott in Plymouth following a domestic disturbance and told that he was in the garden and had a can of flammable liquid with him.
An officer discharged a Taser and, according to eye witnesses, Pimlott was seen "fully on fire from top to bottom". One of the police officers jumped on him to try to put out the flames.
Pimlott was taken to the burns unit at Frenchay hospital but the Independent Police Complaints Commission (IPCC), which is investigating, confirmed on Friday that he had died.
The IPCC said police officers attended Pimlott's address on the evening of 18 April. The caller who had alerted the police advised officers that Pimlott was in the garden with a can of flammable liquid.
IPCC commissioner Sarah Green said: "Our investigation will be looking at what information was known to the officers attending the scene; the officer's rationale for discharging a Taser on a person known to be doused in flammable liquid; whether the discharge of the Taser caused the fuel to ignite; and we will look at training and policies."
She added: "My condolences go to Andrew's family and friends for their loss. This must be a very difficult time for them. Our investigators have already carried out a number of actions, including interviewing the two police officers who attended the incident and ensuring relevant evidence has been secured.
"A post-mortem was carried out and further forensic analysis will be carried out. The IPCC had informed the coroner of our investigation and we will share our report in due course."
Neighbour Jack Fry and his friend Brett Griffiths saw the aftermath of the incident. Fry said: "There were three screams. Brett opened the curtains and at first he thought the house was on fire. But then we saw a man, fully on fire from top to bottom, like you see on a film, with his arms swaying around.
"We saw two police officers appear from the side of the house. One of them jumped on the burning man and put him on the floor. The officers were shouting to each other and the one who had put him to the ground got an old duvet or cover and started smacking the burning man with it. There was steam coming off him and he was groaning. The sight was sickening."
Pimlott's family released tributes to him. His parents wrote: "Dear darling son Andrew, you were a fantastic son to us, you will always be in our hearts and thoughts. We will never forget you."