Police have failed to act on a recommendation to take action over an apparently bungled investigation into the impalement death of a NSW woman in Townsville.

The incident is the latest twist in the extraordinary case of Macksville woman Jenny Lee Cook, who was found dead in 2009 after seemingly impaling herself on a kitchen knife wedged into a wall at the North Queensland home she shared with her prison guard husband, Paul James Cook.

Queensland police took fewer than 24 hours to write the death off as a suicide despite Mrs Cook, 29, not leaving a note and there being no other case in the Queensland suicide register or other coroner databases of a woman killing herself in such a way.

They also failed to fingerprint the knife, search the house for articles used to jam the knife in the wall, check on her husband's whereabouts around the time of death, or seize important potential exhibits or DNA test them.

The knife used in the killing was destroyed before further tests or investigation by the coroner's team could take place.

Mr Cook, who found his wife's body, has denied any involvement in the death. He did admit there had been problems in the marriage.

As a result of his wife's death he received $800,000, which included money from her life insurance, a work cover claim she had been pursuing, her superannuation and from the sale of their house.

After years of lobbying, Mrs Cook's parents, Lorraine and Terry Pullen, late last year convinced Queensland authorities to hold an inquest into the death.

Coroner Jane Bentley found Mr Cook evasive and untruthful in his evidence and said because of the problems with the investigation she could not make a finding of suicide.

She recommended the Commissioner of Police consider whether any action should be taken into the inadequacy of the investigation.

This week – more than six months after the ruling – the Queensland Police Service have not acted.

A QPS spokesman said: "Ethical Standards Command continues to overview the review of the coronial file in relation to the death of Jenny Lee Cook. It is anticipated this matter will be finalised in the near future".

The counsel representing the deceased family in the inquest, Marjorie Pagani, said she had been shocked at the way the investigation was conducted.

"I was appalled by the shoddiness of the investigation and what appeared to be total disregard for the proper coronial and police process and this has resulted in primary and most significant evidence having been destroyed under police authority, despite an ongoing inquest,'' she said.

"The impact on the entire family was tragic. They felt as though they have been done a severe injustice because of police processes and they will probably never forgive the people responsible.''

Fairfax Media has alsolearnt that contradictions in some of the statements were never put to some of the witnesses during the inquest, and that a woman who was alleged to have had a relationship with Mr Cook soon after Mrs Cook's death was also never called to give evidence. Her name has been suppressed.

The Pullens have called for the inquest to be reopened and for the suppression of the woman's name to be lifted.

The coroner's office said the name was suppressed because of allegations of an extra-marital affair.