By Russell Findlay

Surrounded by squalor, odd couple Eddie Cairney and Avril Jones spouted lie after lie in a bizarre attempt to persuade the world of their innocence - that no harm had come to Margaret Fleming.

When I sat down with her so-called carers in the ramshackle ruin of their Inverkip home overlooking the Firth of Clyde, nothing could have prepared me for the claims they were about to make.

Margaret's name first became public a year earlier in October 2016 when Police Scotland issued an appeal for information. Margaret, a 19-year-old with learning difficulties, had not been seen since 1999.

Over the following months, it became clear that this was no ordinary missing person case. Seacroft - the dilapidated home of Cairney and Jones - became a hive of activity as officers dug up the garden and divers searched the shoreline.

Despite extensive and international enquiries, detectives could not find anyone who said they had seen Margaret for almost 17 years - other than Cairney and Jones. The police PR material contained an unspoken underlying message - Margaret was probably dead.

A journalistic contact told me of local rumours that Margaret was alive and well, and living with the Traveller community in England. These claims, it seemed, were being privately peddled by Cairney and Jones while they kept a public silence, having rejected numerous media requests to speak. I decided to make an approach.

Walking through the overgrown garden, I was welcomed by a sign on the front door warning callers about the couple's German Shepherd dogs. Moments later, Jones emerged from the side of the house, accompanied by one of the animals.

What followed was a one-sided, five-minute conversation during which I explained who I was, what I had heard and offered her and Cairney the chance to speak to the media - to tell their story, whatever it may be.

Throughout, she remained mostly mute, gazed impassively and only offered the claim that "nothing untoward has happened". She took my phone number.

Weeks later, I received a call from an unknown number. A gruff male initially refused to identify himself before explaining that he was Eddie Cairney. He and Jones were ready to talk.

While Seacroft's exterior was unlikely to win any home and garden awards, it was nothing compared with what lay inside.

Most rooms were crammed with clutter and junk; the surfaces grimy. Random items, including a wheelbarrow, littered the gloomy hallway. The kitchen appeared to have been unused for years.

An outside wall of one room was missing - a blue tarpaulin doing nothing to stop the autumn chill permeating every damp, dark corner. The stairs were virtually impassable due to further piles of rubbish and missing floorboards.

The couple and their dogs appeared to live in a single room, warmed by a small gas fire. What must once have been an enviable and handsome property was virtually uninhabitable.

Initially, it seemed that Cairney was the senior partner in this curious relationship, which they said was of a business rather romantic nature.

Jones wore the same expression as before - a combination of coldness and bemusement. She was not very talkative. Perhaps she is just smarter than Cairney; cautious of my digital recorder sitting in front of them, capturing every word being spoken.

Frail and unkempt, he began with the conspiratorial claim that "this is a Masonic-driven inquiry the whole thing". The police, Cairney alleged, were out to get him before embarking on a rambling tale involving Freemasons, corrupt council officials, Greenock property deals and Margaret Fleming's late father who was a lawyer.

Cairney's confidence grew and his storytelling became more ridiculous, more outlandish and at times offensive. He shows no warmth while talking about Margaret, deploying ugly terms such as 'lunacy', 'backward' and 'dolly dimple', rhyming slang for simple.

He mocked the police, singling out one officer for particular vitriol, and talked about how he planned to sue them.

Over three hours, all I could do was listen and nod as he went on to tell so many lies that it became hard to unpick them - to work out where one whopper ended and the next one began.

Not only was Margaret alive and well; living with Travellers in England; an international drug dealer and agricultural gangmaster who travelled through Europe on a false passport and used many pseudonyms, but she had actually been inside Seacroft on the night the police came looking for her.

My recorder continued to roll as Jones found her voice, providing an apparently well-rehearsed yarn about how she had the right to claim Margaret's social security benefits for years and how the cash was handed to Margaret during her regular visits home.

Credulity long past breaking point, my photographer colleague captured a series of images of the couple and the home they claimed to share with Margaret before we left.

It then occurred to me, if they were willing to say all this to a newspaper journalist, would they also do so in front of a TV camera? Yes, they would. I returned to Seacroft with a crew who duly recorded a similar version.

Within days of the astonishing interviews being published and broadcast, Police Scotland came calling with a request for me to hand over all my notes and recordings. Once police lawyers secured a warrant at Greenock Sheriff Court, I obliged and also gave a lengthy statement about my experience.

The following day, Cairney and Jones appeared in the dock at the same court, charged with murder, to be later tried at the High Court in Glasgow.

More than 18 months passed before I saw them again, as I swore the oath in front of Lord Matthews, 15 jurors and a packed court which, unusually, contained eight cameras from a TV production company.

The odd couple were now separated by security guards. Jones had the same expression as before while Cairney, now in a wheelchair and looking like death warmed up, stared right at me as I gave my evidence.

Prosecutor Iain McSporran QC chose not to play the three-hour recording of my first interview, instead getting me to read out sections. He voiced the lines of the two accused while I spoke my own. At one point, Cairney grew angry and vocally objected to our performance - prompting a telling off from his lawyer. At times it felt slightly absurd, like an amateur dramatic society's village hall rehearsal.

After giving evidence for several hours and over two days, I was as puzzled as I had been at Seacroft in 2017. Why had Cairney and Jones decided to speak to me?

Did they think that after a year of intensive police activity, they were safely in the clear? Maybe they wanted to use the media to taunt and goad the authorities? Was I regarded as gullible, likely to believe their preposterous stories? And who was really in charge - Cairney or Jones?

Whatever the answers, for them to have willingly told so many ludicrous and brazen lies to a journalist was a damning act of self harm which allowed the police and Crown to use their own words against them.

And while there are very few people to mourn for Margaret, a poor soul who deserved a long and happy life, all that can now be hoped is that Cairney or Jones will do the decent thing and explain exactly how she died and where her remains can be found.