On April 19th, PBS is airing a documentary about the recent discovery of an escape tunnel dug by Jewish prisoners in Lithuania during the Holocaust.

For years, a handful of Holocaust survivors told the story of how they dug that tunnel away from the killing fields where tens of thousands of Jews from the Lithuanian town of Vilnius were murdered.

But it wasn't until this summer that - with the help of new technology - archeologists found physical proof that the tunnel existed.

That documentary was produced by South Portland's Lone Wolf Media.