Joe said that throughout the case the police and prosecution had assured the couple that they had a very strong case and expected to get a guilty verdict.

“So when it was not proven, you were like, what exactly does that mean? There’s something wrong here.”

“It was the fear of knowing that the person who was responsible, in my eyes, was still out there and capable of doing it again,” said Kate.

A common interpretation of not proven was that the jury suspected the accused was guilty, but felt the prosecution had failed to prove the charge beyond reasonable doubt.

Good luck finding that in a law book. As Joe and Kate were to discover, there was no written legal definition of not proven.

Over the years, whenever juries asked, all judges could tell them was that it was a verdict of acquittal, just like not guilty.

Research has also shown that some people thought – incorrectly – that the accused could be tried again if the verdict was not proven.

That has been allowed in exceptional circumstances since 2011 under double jeopardy legislation, but the method of acquittal plays no part in that process.