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.
After years of legal battles, he was granted a retrial in 2007. The 2009 trial saw him acquitted of killing his parents Robin and Margaret, sisters Laniet and Awara and brother Stephen.
Last year the Government agreed to make an ex gratia payment to Bain in the interests of bringing closure to the long-running claim. A full and final payment of $925,000 was accepted by Bain's team.
The couple's Christchurch home is on the market for $440,000. The renovated three-bedroom townhouse is advertised as "still for sale, but a delayed settlement date will be required".
Fairfax called the agent for the house named as "Will" in April. When he answered he told the reporter that he was not David Bain and was selling the house on behalf of a "lady".