Shannon Graham was just 15 when her mum Marion, 54, and 53-year-old Cathy Dinsmore were brutally stabbed to death in a forest just outside the city of Izmir.
Recep Cetin, who was dating Shannon at the time of the killings in August 2011, has been charged with murdering the two best friends.
It has been claimed that he saw them as a barrier to marrying Shannon.
She was my best friend ... It's just so hard to believe.
Shannon Graham, Marion's daughter
In a bizarre turns of events, it emerged that the accused was not 17 - as he had claimed. Bone marrow tests had to be carried out to ascertain his true age of 22.
That development meant that Recep Cetin would be tried over the double murder, alongside his father Eyup Cetin, as an adult.
The trial, conducted in a very different manner to such legal proceedings in Northern Ireland, has proved complicated in many ways.
Recep Cetin's story has changed repeatedly - from claims of mafia involvement, to a confession, to self defence.
Eyup Cetin has always maintained, backed up by his son, that he had no involvement in the murders.
But a key witness has placed both men at the scene.
While a verdict is expected on Thursday, the full truth of what happened to Marion Graham and Cathy Dinsmore - and why - may never come to light.
Those questions have cast their shadow over both families for two years, as they struggle to come to terms with the loss of their loved ones.
In an interview with UTV last year - the first time she had publicly spoken about the case - Shannon Graham said that she and her mum had been inseparable.
"She was my shadow," she added.
Did an enraged Recep turn on both women because Marion was about to put an end to his dreams of marrying Shannon?
UTV's Sharon O'Neill, in her blog Trial in Turkey
Cathy Dinsmore's nephew Robert Dinsmore also spoke out about how hard it had been to face the loss of his aunt.
"She was a wonderful aunt, a wonderful person and very popular - she loved life, loved her holidays, loved her friends," he said.
The double murder in Izmir, 75 miles from the popular holiday resort of Kusadasi where the victims had been staying, caused shock across Turkey and in Northern Ireland.
At the time, the First and deputy First Ministers led expressions of sympathy to the Graham and Dinsmore families and branded the killings a "terrible atrocity".
On Wednesday, with the trial verdict just a day away, UTV's Sharon O'Neill explained that Recep and Eyup Cetin could face more than 60 years in jail if convicted.
Speaking from Turkey, she added: "For the Graham and Dinsmore families, they are hoping this time the outcome will help them begin to move on."