The work presented focuses on the analysis of a police investigation implemented in the computing environment SCY-Lab. The prime objective is to check if the implementation of the situation helps pupils change their conceptions concerning the DNA molecule on the one hand and pupils’ representations of the biological analysis of a crime scene that refers to the professional practices of the technician in scientific analysis. The second objective is to examine the problem-solving processes pupils are faced with. The results of a test with four volunteer pupils at the end of grade 9 show that they are more familiar with the structural aspects of DNA (sequence of nucleotides and double helix) and with its biological level (in the cell and in the core). As far as the understanding of the techniques of biological analysis used as part of a police investigation is concerned, the findings reveal that pupils still do not have a clear vision of what the term “DNA profile” means, even if they have understood how genetic profiles can be obtained. The pre-experimentation was useful to improve the resources, instructions and activities performed on the platform. They will then be given to a greater number of pupils.