Kay Gilderdale insists she did the right thing for her daughter
Almost three-quarters of people support assisted suicide for someone who is terminally ill, a BBC poll suggests.
However if the illness is painful and incurable, but not fatal, then backing falls to slightly under half.
The survey of just over 1,000 people was carried out for Monday's edition of BBC One's Panorama programme.
It features Kay Gilderdale who was cleared last week of attempting to murder her daughter Lynn, who had the chronic fatigue syndrome ME.
Ms Gilderdale admitted aiding and abetting the suicide of her 31-year-old daughter and was given a 12-month conditional discharge.
Lynn was found dead at their home on 4 December 2008.
The survey found that 73% of those asked believed that friends or relatives should be able to assist in the suicide of a loved one who is terminally ill.
But, if - as in the case of Ms Gilderdale's daughter - the illness is not terminal, support for assisted suicide falls to 48%.
Lynn was bedridden by the age of 15, and was admitted to hospital more than 50 times with a succession of serious illnesses over the next 16 years.
Ms Gilderdale told the programme: "I know I did the right thing for Lynn. She's free and at peace where she needed to be. Whatever the consequences, I would do it again."
The survey was carried out earlier this month and the figures are broadly in line with previous surveys.
Last year, the Director of Public Prosecutions issued guidelines on when assisted suicide cases should be taken to court.
But campaigners have said there still needs to be more clarity in the law.
Panorama: I Helped My Daughter to Die is on BBC One on Monday 1 February at 2030 GMT.