I was only a year old when the UK's deadliest terror attack shocked the world. In December 1988, Pan Am flight 103 exploded - killing all 259 people on board as well as 11 on the ground in the Scottish town of Lockerbie. I was a teenager by the time Libyan intelligence officer Abdelbaset al-Megrahi was convicted of the bombing in 2001 and, when he later died, I thought that was largely the end of the story. As part of a Radio 4 Intrigue podcast series, I had an opportunity to delve into this complex case with fresh eyes. The deeper I dug, the more complicated Lockerbie became and there have been times that I don't know what to believe.