Scottish health chiefs stored a woman's liver in a fire-proof safe after fears wife killer Malcolm Webster would burn down the hospital if he knew where vital evidence against him was kept.

Webster was sentenced to 30 years jail in July 2011 for killing his first wife, Claire Morris, after drugging her and staging a car crash in Scotland in 1994.

He also tried to kill Aucklander Felicity Drumm in New Zealand in a copy-cat car crash five years later.

In March, Webster won the right to appeal his murder conviction. He will appeal at the Court of Criminal Appeal in Edinburgh on September 26.

In May last year, Drumm, 50, told Scottish newspaper The Mail she felt lucky to be alive after a car crash north of Auckland in 1999, which she believed Webster deliberately caused.

The convicted murderer disappeared soon after the incident with her life savings.

Scotland TV station STV reported that Dr James Grieve, a forensic pathologist at the Aberdeen Royal Infirmary, revealed in a new book that a sample of Morris's liver and other organs were stored in wax blocks in a special storage unit since her death in 1994.

Tests carried out on the samples in 2007 as part of the investigation into her death found a 92 per cent chance that the sedative temazepam was in the liver. It resulted in police reopening the case against Webster in 2008.

The samples were then stored in a flame-proof container after fears Webster would burn down the hospital if he knew where the evidence against him was kept.

STV quoted Grieve as saying: "I have no doubt that, had he known it would be a problem for him and had he known the location of Claire's samples, he would not have hesitated to burn the storage facility down."

- © Fairfax NZ News