21 April 2021
Robert Horselenberg on his student cold-case team

How do you solve a murder?

Imagine: 15 years ago, a woman was murdered. Now a cold-case team has reopened the case. The detectives discover that during the original investigation, no samples were taken from the victim’s lips or from under her nails. Should the remains be exhumed? This is the type of issue that a select group of master’s students is working on during the Cold Cases project.




Forensic technology is not a magic bullet. The core of detective work—the pillars that underpin the development of plausible scenarios—are dry facts. This is why Horselenberg’s team spends much of its time studying the file and establishing those facts. Who is the victim, who were they in contact with, what was the cause of death, and—above all—what is not known? Only then do they turn to what may have happened. After all, the outcome is known: someone is dead. But what happened in the hours and minutes leading up to that?

“Our students work in pairs to make a certain scenario as strong as possible,” Horselenberg explains. “It may be plausible that the victim had a secret lover, for example, and that person is the culprit. You look at what facts support this assumption, and what information you need in order to prove it. In this case, it would be a good idea to speak with the victim’s friends. Especially when you consider that witnesses, family, current and ex-partners and neighbours contribute to three quarters of the cold cases that end up being solved.”

Fresh eyes

Although students can create fake social-media accounts and consult experts, they are not allowed to contact anybody involved in the file. At the end of the investigation, they write an extensive report with recommendations that is sent to the police and the Public Prosecution Service. Unfortunately, these reports are then put on a shelf, where they sit for years. Horselenberg attributes this to chronic understaffing of the cold-case teams, which are lumped with missing-persons cases in addition to unsolved murders.

“We do very serious analyses, make suggestions and come up with points the police hadn’t thought of. This is partly due to the fresh eyes and uninhibited perspective of our students; they’re not encumbered by experience.” That lack of experience can be an advantage, he says. “In cold cases, detectives who have done their job just fine for 30 years can easily fall into the trap of: well, that was a junkie and they talk nonsense. So we don’t need to interview that person again—whereas doing so might just pay off. In short, you have to approach cases like these with an open mind.” Horselenberg is in favour of a national cold-case team comprising inexperienced detectives with strong critical-thinking skills, who work according to a protocol. At present, no such protocol exists.

Meanwhile, cold-case education has proven its worth as a learning tool for students. “There are students who come to Maastricht specifically for this course. And alumni tell me that they’re still reaping the benefits of the knowledge and skills they acquired with us. In that sense, the cold cases we discuss are of great educational value whether or not the police actually do anything with our investigations. Though it would be nice, of course, if we could help to bring about closure for the next of kin. They want nothing more than to finally turn the page on that chapter of their lives.”

In current and cold cases alike, DNA leads to a genuine breakthrough in less than 3% of cases.
By: Jolien Linssen (text), Arjen Schmitz (photography)