Epithelial cells are biological traces that, despite not be visible to the naked eye, are increasingly important in forensic cases. This becomes more important when others evidences were not found at the site of the event, such as optimal fingerprints for comparison, allowing a faster identification of those involved in a crime and which mean a lower cost of analysis. Similarly, the absence of biological fluids that involve a finding of higher concentrations of genetic material, allowing the performance of DNA analysis for comparison with genetic profiles of suspects. The present work is dedicated to the knowledge of epithelial cells as biological evidence useful to be raised at the crime scene and shows the different findings of researchers in relation to their collection from various surfaces, in which these are deposited. In addition, some techniques for obtaining them will be cited and studies will be mentioned that have evaluated conditions to have them present at the moment of their lifting, since a loss of concentration or poor collection of these cells from the scene of the crime, could mean not obtaining an amount enough of genetic material to be amplified and thus not be possible to compare with an indubitable sample of the victim or offender.