The brother of a Gisborne woman found dead in a police cell - the day after she was found guilty of murdering their father by torching his home - says he feels no sorrow for the loss of his sister.

Lynne Maree Martin, 63, was yesterday found guilty of the murder of Ronald Allison, 88, who died in 2013.

This morning, police said there had been a death in custody at the Gisborne Police Station overnight.

John Allison confirmed to the Herald his sister had died in the cells.

“I can’t feel sorry for someone who killed my father,” Allison said.

“There is no emotion just right at this moment. She has been convicted of killing my father.

“There is no sorrow.”

A police spokesman said they were making inquiries on behalf of the coroner after a death at the station.

63-year-old Lynee Maree Martin, who was yesterday found guilty of the murder of 88-year-old Ronald Allison. Photo / S Curtis

“The cause of death will be a matter for the coroner to determine, and the IPCA have been notified,” the spokesman said.

Martin was being held in the cells at Gisborne Police Station awaiting being transported to prison.

Martin was on trial for setting fire to her father’s Te Karaka home in January 2013.

Expert evidence heard by the jury indicated the fire started through a pot of oil or fat being left to ignite on a hot stove element.

Martin had been convicted of arson in Australia in 1999 after she set fire to two vehicles at her partner’s house in New South Wales.

Murderer sobs as verdict read

A jury took about two hours on Wednesday to find Martin guilty of having burned her father alive by deliberately setting fire to his beloved Whatatutu farmhouse - the place he hoped to live out his life.

Martin was stony-faced, showing little emotion during the 12-day trial, but burst into tears and sobbed loudly when the verdict was read.

Martin’s father was largely immobile, his eyesight, hearing, and sense of smell were failing him, and he’d taken a sleeping pill as he did every night before going to bed.

John Allison was at his father’s house until just after midnight, having helped with the bedtime tasks as he did nightly.

However, just before drifting off to sleep, Russell Allison had told him about a disturbing phone call he’d received from Martin earlier that day. John Allison’s last conversation with his dad had been about the need for them to step up security at the house.

Confronted later by the fire scene and the few remnants of his family home and his father’s life, Allison immediately told police at the scene he suspected his sister was responsible.

An investigation led to cellphone polling data which put Martin in Te Karaka only hours before the fire. However, charges weren’t laid against her until last November after two police operations, including an undercover one that ran for three years.

Martin had revealed to a young undercover cop known as “Millie” that she knew how to start a delayed-ignition fire using a pot of oil, and told her “arson is difficult to prove”.

Police tasked fire experts with carrying out a series of tests using pots of oil and cooking lard, which confirmed it was the same method used to start the blaze.