And although the McNally family have never voiced criticism, others have raised questions about what they perceive to be shortcomings in the early days of the investigation – particularly how and why McCullagh’s alibi was initially accepted.
Neil McGuinness, who took over the investigation a few days in, said he doesn’t believe the criticism is fair.
“Every decision that I make is made on the best available evidence at a point in time,” he said.
“One of the first things that I did was have an officer contact YouTube in America to ascertain whether this footage was live streamed or not.
“YouTube sent us a very quick response back to say, yes, we confirmed that was live streamed, you know, and all appeared to be in order from their point of view.”
He said that when the issue of McCullagh’s alibi was later revisited, considerable efforts had to be undertaken just to seize the computer.
“That work couldn’t have been done within the time periods we can hold people in custody [on the initial arrest].”
It is almost taken for granted in Northern Ireland that the gap between a suspect being charged and their eventual trial will be lengthy.
For Catherine Kierans, there is a balance in this argument.
She points out that fresh, important evidence, such as the discovery of a photograph of McCullagh wearing a hat and wig similar to the person of interest caught on CCTV was found only a short time before the trial.
She’s also hopeful that in the long-term AI could be used to help police trawl through CCTV faster.