I can’t remember if we’ve discussed it here before, but, for the past several years, German authorities have been hot on the trail of a mysterious serial killer. Called “the woman without a face,” the killer was thought to have murdered dozens of people over a span of 15 years. Here, by way of background, is a recent clip from the UK paper The Guardian:

…And now, Bad Kreuznach finds itself at the centre of one of the most bizarre, high-profile murder mysteries in the country’s history – the search for an apparent serial killer whom police and prosecutors call, simply, ‘The Woman Without a Face’. They have no fingerprints to go on. No witnesses. No description. What they do have is a trail of DNA, now stretching back 15 years and across three countries – as well as a grisly new reason to put a face to her double helix. A case that had for years been gnawingly disturbing, yet still fairly obscure, has leapt on to the front pages of German newspapers. For it appears now that the mystery woman may not only be a killer, but a cop-killer.

In April 2007, Michèle Kiesewetter, a 22-year-old policewoman from an elite drugs squad, was taking a lunch break with a colleague in their BMW patrol car in Heilbronn, nearly 100 miles from Bad Kreuznach. Two people climbed into the back seat and shot the officers from behind, killing the woman and seriously injuring her 25-year-old partner. The assailants struck so quickly their victims had not even drawn their weapons.

As dozens of green-uniformed officers, carrying a smiling portrait of their murdered colleague, paraded at her funeral, the case shocked and moved the country. It also sparked one of the largest criminal investigations in German history – with results that at first puzzled, then stunned, the investigators.

The only clue was microscopic traces of DNA, found on the centre console and the rear passenger seat of the BMW. And when the samples were finally fully secured, tested and compared with Germany’s central crime database nearly three months later, there was an extraordinary match – from two quite different murder scenes stretching back a decade and a half. The ‘Woman Without a Face’ had, it seemed, struck again…