David Bain is starting afresh, beginning with his new name - William Davies.
Bain, who was acquitted of the murder of his family in 2009, has taken the surname of his wife Liz through a deed poll process.
His new name William David Cullen Davies is now officially recorded on his birth certificate, Fairfax reported. Before the change his full name was David Cullen Bain.
It is believed the couple, who have a young child, are moving to Australia to start afresh.
Bain was first found guilty of the murder of his five family members - Robin, 58, Margaret, 50, Arawa, 19, Laniet, 18 and Stephen, 14 - in May 1995 and jailed for life with a minimum term of 16 years. They were fatally shot on June 20, 1994 in their Dunedin home.