Philip Nisbet was found dead in his Christchurch home on May 4, 2009.

In 2013, Helen Milner was found guilty of drugging her husband in order to get the life insurance payout.

Four years earlier, she had convinced police her husband killed himself.

But Lee-Anne Cartier, the victim's sister, felt something was off and began her own investigation.

NZ Herald reporter Kurt Bayer followed the case through the courts - it was dubbed The Black Widow case.

Go to this episode on rnz.co.nz for more details