Mr Dornan appealed to the local community to bring any information they had to the police, so that his daughter's killer could be brought to justice.
"Whatever you've seen - how little, how big, how small, come forward," he said.
"This animal killed an innocent, defenceless woman in cold blood.
"However little you know, come forward, and he'll be off the streets tomorrow - before he does this to somebody else."
Jennifer Dornan's body was found in her burned out Hazel View home in the Lagmore area of Dunmurry on Sunday.
It was initially thought that the popular community figure - who had only celebrated her 30th birthday in May - had died in the blaze.
But yesterday the PSNI revealed that they had launched a murder hunt. A post mortem yesterday found evidence that Ms Dornan was already dead before the fire was started.
At the hundred-strong vigil, Jennifer's sister Claire was too overcome with emotion to speak.
Jennifer's uncle Paul Donnelly described his niece as "an angel".
"She would have done anything for anybody," he said.
"She'd have gone out of her way to help anybody - that's the sort of person she was.
"I can't believe what has happened.
"It was bad enough thinking that she died in a tragic accident, but to find out that somebody murdered her, and then set her house on fire to cover it up - it's a disgrace. This person needs to be taken off the streets as soon as possible."
Clairsey Colette, a friend of the murdered woman, has set up an online campaign to raise money to help Jennifer's three children - Abi (4), Martin (8) and Jayden (6) - in the aftermath of their mother's death. They had been staying with their grandmother at the time.
In just two days the campaign has raised £12,000 from 857 donations.
At the vigil, Jennifer's friend, Tanya Watson, said: "Everybody loved her - no one had a bad word to say about her.
"Jennifer's memory will live on.
"Not one person here tonight will ever forget Jennifer - and the person that she was."
West Belfast Sinn Fein MLA Jennifer McCann, who attended the emotionally-charged vigil, said: "I want to offer to the family tonight the sincere sympathy and the condolences of this community - and especially to Jennifer's mother and father, and particularly to her three young children.
"We really feel your sense of loss. This news has sent shockwaves through the community, who have rallied round her family.
"I am urging anyone in the community with information which may assist the police inquiry into Jennifer's death to come forward right away."
"This is a time for calm heads and the community needs to support the family and help the police get on with their job of finding Jennifer's killer."