AS a senior detective in the RUC through the darkest days of the Troubles, Alan Simpson knows more than most about the so-called "dirty war" waged on the streets of Northern Ireland.
He led the much-maligned investigation into the murder of Belfast solicitor Pat Finucane; despaired at the failure of the Omagh bomb investigation to bring anyone to justice; and fought against a rising tide of paramilitary racketeering in a career described by one commentator as an "emotional tsunami".
The retired detective superintendent was in Belfast yesterday for the launch of his book Duplicity and Deception: Policing the Twilight Zone of the Troubles, and told the News Letter of his motives for writing his personal account.
"I couldn't have written this book a few years ago as it would have put certain people in danger. I think the story needs to be told and now is the right time in my view," he said.
"Some people hear about the book and think I am attacking the RUC, but that is not the case at all. I think the book will claw back some credibility for the RUC that was lost due to a few high-profile, how should I put it, 'black marks'."
Softly spoken and good-humoured, the ex-detective gave no outward indications of his past employment in the policing pressure cooker.
It was telling in his change of tone, however, that as he paid tribute to the colleagues he valued as making the greatest contribution to the policing effort, many had become victims of terrorism themselves.
"When I was investigating the kidnapping and subsequent murder of the German diplomat, Thomas Neidermayer, we had to move hundreds of tons of rubbish at Colin Glen rubbish tip while pretending to be an environmental action group," he said.
"One of my closest colleagues was particularly dedicated to the hunt for the body, which eventually led to convictions, but was killed by the IRA and became just one of many excellent detectives murdered over the years."
Surprisingly open and honest for someone more accustomed to the shackles of secrecy, the long-serving ex-officer spoke freely of his admiration for campaigners such as Raymond McCord.
Mr McCord, whose son was murdered by a UVF gang in 1997, continues to demand answers about the role of police informants in his son's death – and the author wishes him well in his quest.
"The are many questions to be answered and the McCord case is just one that will probably unravel as time goes on.
"Scappaticci is another one that we definitely haven't heard the last of," he said.
"Special Branch saved many, many lives throughout the Troubles, and in the main did a brilliant job, but at some point they seemed to lose their way.
"As a CID detective I was accountable to my superiors and ultimately I had to defend my actions and have my investigations scrutinised in the courts – Special Branch did not and that led to problems."