ITV has ordered an inquiry into a documentary which wrongly claimed to show the dying moments of an Alzheimer's patient.
Malcolm Pointon was diagnosed with Alzheimer's aged 51
Publicity for the ITV1 programme said composer Malcolm Pointon, 66, "passed away" in the final scene - when he actually died three days later.
Film maker Paul Watson has blamed the broadcaster for mishandling the story.
ITV chairman Sir Michael Grade has appointed media law firm Olswang to carry out the investigation.
The broadcaster was forced to admit the footage was of Mr Pointon slipping into unconsciousness after his brother Graham revealed the truth.
ITV has said the documentary, to be shown on 8 August, will include a clarification.
He said: "We need to discover why the film was originally understood to include the moment of death only for it to be established that he died some days after the last scene in the film.
"This is a very serious matter. I am on record as taking a zero tolerance approach to deliberate deceit in television programmes.
"I intend to establish the facts in this case as quickly as possible. I will publish the conclusions of the report and then take effective action as necessary."
Earlier, in a statement, ITV said it said it had made the clarification about the footage a day after film maker Mr Watson had alerted them to his concerns.
But Mr Watson claimed ITV refused his request to make clear the programme did not show the Cambridgeshire man's final breath.
He told BBC Radio 4's Today programme :"I offered ITV a way of resolving this issue straight and clean, and they turned it down.
"I asked to put in five words to explain absolutely that the picture you are looking at this moment is not of Malcolm's death.
"They turned it down at that instant and came back to me much later and said 'maybe it is a good idea and we lost time'."
He claimed to have been made a "scapegoat" and insisted he "did not set out to deceive".
Mr Watson spent 11 years working on the project, charting the decline of Mr Pointon and the devotion of his wife Barbara.
Mr Pointon never regained consciousness after being filmed in ITV1's Malcolm and Barbara: Love's Farewell - a sequel to Mr Watson's award-winning Malcolm And Barbara: A Love Story, which chronicled Mr Pointon's early battle against the illness.
The publicity material, released to the media, said: "The film ends when [Mr Pointon's wife] Barbara calls Paul to ask him to come as Malcolm is about to die.
"In moving scenes, Malcolm is surrounded by his family and Barbara strokes his head as he passes away."
Mrs Pointon told BBC Radio Five Live the fact the film did not show the exact moment of her husband's death was not important.
Mrs Pointon said the film's message was in danger of being lost
She said: "I want people to know that Paul filmed Malcolm's last semi-conscious moments, because after that... Malcolm slipped deeper and deeper into unconsciousness, into a coma, and he just faded away."
She added: "Does it really matter whether it [his death] was two minutes, two days, two weeks after that point? It doesn't alter the fact Malcolm died of this illness.
"And that's the message I wanted to get through, that Alzheimer's kills."
The Alzheimer's Society said Mr and Mrs Pointon had made a "brave decision" to highlight the effects of the disease and it hoped the controversy surrounding the final scenes would not detract from the documentary's message.
Director of external affairs Andrew Ketteringham said: "There is nothing fake about Malcolm's devastating decline."
ITV director of television Simon Shaps said: "The film maker responsible... has now confirmed that the film does not portray the moment of Malcolm's passing, which was in fact some days later.
"This will be made clear at the end of the film on transmission and should have been made clear earlier."
ITV's admission follows controversy over promotional footage for the BBC One documentary, A Year With The Queen, which the BBC promoted as showing the monarch storming out of a photo shoot, when in fact the scenes were out of sequence.
The BBC and film maker RDF Media later apologised and an inquiry is under way.