I first became interested in forensic science in 1987 when I was a physics student at the University of Applied Sciences in Rijswijk. I did an internship in the tool-mark and firearm department, and although I really liked the work there, when I graduated there were no vacancies at the laboratory. Working in an industrial environment appeared more attractive to me than working for the government at that time, so I started my working life at Oce Nederland B.V., conducting research on digital photocopying machines.

Some 3 years later, vacancies were advertised in the physics department of the Netherlands Forensic Institute (NFI). My desire to work in the forensics field was undimmed. Furthermore, the experience in image processing that I had gained at Oce was useful, because we were developing databases on shoe prints and tool marks at NFI. I decided to specialize in tool-mark and shoe-print investigation, also receiving training as an expert witness in this field. After 3 years, I gained Dutch court approval as an official expert witness.

A reorganisation of the institute in 1995 allowed me to use my image-processing knowledge as part of a new group in the institute's firearm department. At that time, commercial systems were being developed for the automatic comparison of cartridge cases and bullets. In order to evaluate these systems, I conducted a research project on comparison algorithms. As a second research project, I started working with the pathology departments of NFI and the University of Amsterdam on the use of computerized tomography scans for determining the caliber of a bullet in a living person.

The Importance of (Inter-)Networking

Apart from attending and organizing meetings on forensic sciences, and working for 3 months at the Japanese Institute for Science and Technology on a grant for video image processing, I discovered that the Internet was a great way of building up my network. In 1994, I started my own Web site ( with forensic information and links to other sites. At first, there were discussions with the director of the institute as to whether it was appropriate for a government employee to have such a Web site. But, when he was visiting institutes abroad, he realized that the Internet would soon be useful, so he supported me and took an interest in the resulting developments.

Staring from a very basic version, the site developed within a few years into a well-known database of unexpected popularity among the forensic community. I received several invitations to give lectures on how to use the Internet for forensic science in those days. Because so many people e-mailed me asking questions, I decided to start a forum on forensic science, where people can post their questions anonymously. It has since become apparent that lawyers and suspects too make use of my Web site, and sometimes the answers have even been used in court.

The first time I actually had to appear as a witness in court is still clear in my memory, partly because the so-called "ballpoint pen case" drew a lot of publicity. A woman in Leiden, the Netherlands, had been killed with a ballpoint pen, which penetrated her brain through her eye. The suspect told his psychiatrist that he had killed his mother with a crossbow and this ballpoint pen and was convicted. However, the case was reinvestigated when it reached the appeals court. The father, and several experts, did not believe that the woman could have been killed with a crossbow.

This is where the forensic experts came into play. We conducted ballistic experiments in gelatin with a high-speed video camera in order to examine the condition of the ballpoint pen after it had been shot with the crossbow. Under special conditions of the crossbow, it appeared that it was in fact possible to fire the ballpoint pen without damaging it, implying that the scenario was technically possible. Challenging experiments had to be done in a short time under high pressure.

When I look back on this case, I remember the considerable media attention at that time. Also, this case followed me for a long time as an expert witness; even 5 years later, attention is given to this case in journals and books. Another important lesson was to understand the significance of forensic research teamwork in such complex cases: Together with the departments of chemistry and pathology at the forensic laboratory, we wrote a report that proved to be useful in deciding the case.

What You Should Know

Forensic casework is sometimes unpredictable, such that one generally does not know what will happen the next day. At the same time, though, much of the work is routine, and care must be taken to handle the administrative procedures correctly so that evidence is admissible in court. Meetings and communication with the police and courts should also be handled carefully. As a forensic scientist, one is given much responsibility and needs to work well in a team, while also maintaining an independent opinion.

I greatly enjoy doing forensic research, mostly because of the variety of activities involved, but one of the downsides is the pressure of working to strict deadlines. Sometimes, one also has to deal with emotional issues, as when examining child pornography images, for example.

Depending on where you work, the job is reasonably well paid for a 36-hour workweek. Salary depends on experience and education and is between EUR 20,000 and 55,000. Dutch government employees generally do not expect their salaries to increase very rapidly.

Although there is a special training program at NFI, most skills have to be learned on the job. The formal education is, however, a good basis for doing investigations and finding scientifically correct solutions for new developments. The most effective mentors are colleagues in the laboratory itself, but colleagues from labs abroad can also be important in this respect.

My advice: As a young scientist who would like to enter forensic research, you should just apply for the job. Once you are in forensic research, there are many possibilities to expand your horizons.

During the '90s, the field of image processing and pattern recognition in forensic science developed swiftly, and I had to testify several times in court on the investigation of video evidence. In 1999, the Netherlands Forensic Institute was formed by merging the Netherlands Forensic Laboratory and the Laboratory for Forensic Pathology, and I became a research and development coordinator focusing on developments in digital evidence at the new NFI. Later, this role was expanded to include R&D coordination for the Dutch High-Tech Crime Units of the police.

This move meant I was less involved in casework, so I had time to write my doctoral thesis, "Content-Based Information Retrieval from Forensic Image Databases," and I successfully defended it in June 2002. In the future, I expect to work more in image processing and biometric devices. My academic colleagues think of my move to forensics as something that is really appropriate to me as a person.