Elaine Duffy, 34, was stabbed in the chest on Tuesday afternoon during the party at a house in Beswick, Manchester, hosted by National Lottery winner Peter Horsfall. Police were questioning Mr Horsfall, 47, and seven other party-goers yesterday, and waiting for other guests to sober up so they could interview them about the stabbing.
Mr Horsfall, a drainage worker, won pounds 94,000 in the lottery five weeks ago.
Mrs Duffy, married with three children aged 12, 13, and 16, was stabbed three times in the chest with a kitchen knife.
One witness said: "Pete [Horsfall] came out of his house in a tremendous panic screaming at us to call an ambulance.
"I went over to see what had happened and I could see the women's head on the settee and all these lads round her."
Paramedics and police arrived to find Mrs Duffy dying from chest wounds inside the house. She died later at Manchester Royal Infirmary.
A neighbour said: "Pete and at least 10 people must have been taken away by police but we heard the killer had already run off."
She added: "Pete had won the lottery just five weeks ago but was not intent spending the money. He just used to invite people round for drinks because he is that kind of man.
"There there had never been any trouble at his home before."The neighbour went on: "Pete is a thoroughly decent bloke who won the lottery five weeks ago then handed the winnings straight over to his kids."
Eight men have been arrested and held by police in connection with the murder.