The police officer who instigated a surveillance operation on the house where pensioner Roseann Mallon was murdered has burnt all his notebooks, a coroner's court has been told.
The former Royal Ulster Constabulary (RUC) Special Branch detective inspector destroyed his police journals and diaries when he retired to stop them falling into the wrong hands, an inquest heard.
The officer, who has been granted anonymity, said: "I was subject to two very serious threats.
"I did not want those (journals) in my home in the event of a burglary that could expose my family to further threats."
The ex-RUC man, known only as P3, was the most senior figure in Special Branch in Dungannon at the time of Ms Mallon's murder in May 1994.
He said he never considered handing his books back to the police for future reference during trials or inquest hearings.
"There was no requirement, I never even thought about it," he added.
P3 also said he was unaware that the Retired Police Officers Association, of which he is a member, was offering advice on how to avoid giving evidence at inquests.
Roseann Mallon, 76, was gunned down at her sister-in-law's home on Cullenrammer Road, Dunagannon, Co Tyrone, on May 8 1994.
The Ulster Volunteer Force said its mid-Ulster unit had been responsible and was targeting relatives of the pensioner who were involved in the republican movement.
The case is one of 29 Troubles-related inquests that has been awaiting a full hearing for decades.
It is shrouded in controversy after secret army spying equipment was discovered in a field overlooking the murder scene.
Giving evidence from behind a screen, the retired officer rejected claims by Barry Macdonald QC, representing the Mallon family, that burning the books could give rise to the suspicion there was something to hide.
He said: "I am a truthful person.
"My integrity is intact."
He also defended Special Branch as a professional organisation which played an integral role in ending terrorist activity in Northern Ireland.
He said he was never involved in collusion; was not aware of it happening and would not have condoned such activity.
He said: "I know of no time that it (collusion) happened. I have never known it myself and I would not condone any of my staff doing it."
Notorious loyalist killer Billy Wright and two others were arrested and taken to Gough Barracks in Armagh but they refused to answer any questions and all three were released without charge after several days.
The former detective categorically rejected claims that Special Branch had passed information with the UVF.
"Special Branch was a credible organisation which delivered intelligence throughout Northern Ireland," he added.
Although he was unable to recall the number of agents his office was running at the time of Ms Mallon's shooting, he insisted that, under his watch, relationships between handlers and informants were professional.
"There were informants in all organisations. It was a professional relationship to gather intelligence at great risk to us and our informants to try and bring an end to terrorist activity," said P3.
The court also heard that P3 left Dungannon Special Branch unit mid-1994.
The inquest, now in its third week, is being heard before High Court Judge Mr Justice Weir at Belfast's Laganside complex.
Ms Mallon's nephew, Christopher, was in the public gallery but declined to comment on the case.
Proceedings have been adjourned until next Monday.