They lay hidden for centuries, a gruesome 13th-century secret left untouched until chanced upon by workmen digging the foundations for a new Norwich consumer haven.

But this week, the mystery behind 17 skeletons discovered during excavations for the Chapelfield shopping centre in 2004 will be unravelled before an audience of millions – and with it, an unsettling tale of persecution.

Combining detective skills and 21st- century forensics, a team of experts pieced together evidence for a BBC2 History Cold Case programme to be broadcast on Thursday.

It will reveal that the bodies, found down a well, are believed to have been murdered or committed suicide.

The reason for those people’s deaths? They were Jewish.

Giles Emery was working for the Norfolk Archaeological Unit when the “one-off” remains were found and has followed their fate ever since.

“What happened is a tragedy, but now we can see these people as human beings again and they are able to tell their story,” said Mr Emery, who now runs Norvic Archaeology.

He and fellow researchers knew they were on to something special when the bones were found accidentally by a builder about five metres below ground. Of the skeletons, 11 were small children.

However, their funding and studies could only take them so far, and, when the BBC first contacted them two years ago, it proved an opportunity not to be missed.

Having visited the site earlier this year, the real breakthrough came through when analysis of some of the bones revealed they had DNA consistent with Jewish communities and belonged to family members who had lived in the area for many years.

It proved a key finding. The group had lived in a time rife with anti-Semitism as Europe became more Christian. Norwich was known too to have had a thriving Jewish community since 1135: it had lived just a few hundred yards from the well.

Miri Rubin is a professor and historian at Queen Mary, University of London and was part of the most recent studies. She said: “There was a real deepening of this sense of Jewish evil, so it is a picture of worsening and, ultimately, the age of expulsions.”

With natural death ruled out, and neither the Christian nor Jewish communities ever having been found to bury members of their communities in this way, the team was left with only the bleakest of conclusions.

Mr Emery was one of those present when the findings were first presented to a recent gathering of historians in Norwich Guildhall. He said: “It was astounding when we found out.

“Everyone recognised that it was quite an unusual thing to be able to find out something we couldn’t have done a few years ago, and now we’re just trying to spread awareness of it.”

History Cold Case will be on BBC2 at 9pm tomorrow night.

john.owens@archant.co.uk