A former police detective is working for free to try to overturn Mark Lundy's conviction for the brutal murder of his wife and daughter.
Michael Chappell, now an independent forensic computer expert, is helping with Lundy's appeal to the Privy Council, to be heard next month.
Lundy is serving a life sentence for the murder of his wife, Christine, and their 7-year-old daughter Amber at the family's Palmerston North home in August 2000. In 2002, the Court of Appeal threw out his case and increased his minimum non-parole period to 20 years.
Chappell left the police in 1999, and was later charged with 10 dishonesty offences. He was convicted of some in 2002 and did jail time.
Chappell said he had worked for free for 2 years on the Lundy case, building on the work of former police forensics expert Dr Allan Watt. "Someone's got to do it," he said.
