Cold case calendar spread among all Dutch prisoners after successful experiment

The Dutch police decided to spread their 'cold case calendar' among all 30 thousand detainees in Dutch prisons. An experiment involving the calendar, which contains details about 52 cold cases - one for each week, being spread in five prisons proved to be successful, ANP reports.

The idea behind the calendar is that prisoners can provide tips about the cold cases. "The experience of the police and judiciary shows that prisoners have relatively high levels of knowledge about committed crimes", the police said on Tuesday.

The experiment showed that the calendar did not cause unrest in the prisons. Two thirds of the prisoners who took part in the experiment found the calendar to be a good idea. Though a minority refused to accept it because they did not want to be "snitches".

"It's hard to say how many tips from prisoners the calendar led to", initiator Jeroen Hammer said, according to ANP. Many tips are made anonymously. And the cold cases in the calendar can also be viewed on the police site, so tips may have come from outside the prisons.

What is clear is that more tips were received. In the first five months of this year, the police received 160 tips about the cases in the calendar - about the same number as the police receive per year on average. Almost half the tips related to the murder of Nicky Verstappen. Two cases were reopened based on tips received.

In order to maximize the chance of success, the texts on the calendar were also translated to English, Spanish, Arabic and Russian.