The woman who killed her elderly father by setting his house alight has died suddenly, the day after she was found guilty of murder.

Lynne Martin, 63, was found dead in the cells at the Gisborne Police Station on Thursday morning, Stuff understands.

She was being held there before being transferred to prison, after a jury on Wednesday afternoon found her guilty of murdering her father, Ronald Allison.

Allison, 88, died when his house near Te Karaka, about 30 km from Gisborne, burned to the ground in the early hours of January 25, 2013.

In a statement on Thursday afternoon, police say they are, on behalf of the Coroner, investigating the death of a person in custody at Gisborne Police Station.

“The cause of death will be a matter for the Coroner to determine, and the IPCA have been notified,” says a spokesperson.

-Marty Sharpe/Stuff.