A couple of years ago, during the construction of a shopping centre in Norwich, a dry well shaft was excavated. In it were found the bodies of 17 people, including 11 children. It was deemed a suitable case for the BBC's forensic team to investigate.

Medieval Norwich was an insanitary place, we were told, and it was originally thought that these unfortunates had probably succumbed to one of many endemic diseases. However, the truth turned out to be far more chilling.

As Professor Sue Black and her team discovered, if they had been victims of disease, they would all have been buried in Christian fashion. These bodies had been dumped in the well.

DNA samples indicated that the victims were Ashkenazi Jews. It did not take a forensic detective to tell us that there had been foul play (although this was exactly what a forensic detective did conclude).There had been a population of 150-200 Jews in Norwich during the period, brought over from Europe to lend money - an un-Christian occupation. They had been protected by the Crown, but in the 13th century this protection had begun to break down and there were records of attacks against Jews.

The bodies in the well seemed to be victims of more than a casual hate attack, however - this was ethnic cleansing, and as the facts unfolded what was revealed was truly shocking. In the best scenario, these were Jews who had been killed in a fire, or beaten to death and then the bodies disposed of. However no one could rule out the horrific possibility that this family (for the DNA and a reconstruction of the victims' faces showed that some at least were related) was rounded up and thrown alive down the well, where they would have died of the trauma, slowly bleeding to death, or maybe of crush asphyxia, where the breath is squeezed out of the body.

The people who had originally discovered the bones were brought together to be told what the investigations had uncovered, and to see the reconstruction of the victims' faces. When they were informed that their city had been responsible for an episode of mass murder they were visibly appalled. But then so would anyone be who watched this upsetting but truly moving hour of television.