the research involves a ser ies of analysis of two real cases, and that in Guatemala the violent death of two people, one of this is a woman and another process of investigation the death was a men. It was focused on the study of two specific cases t hat are similar and where through fragments prinsts finger collected in the crimescene, could be essential to the investigation and to obtain in one case a conviction twenty -five years in prison for the crime of murder and in the other case the accused or defendant has not yet been capture d, but currently has an arrest warrant. All these advances in research and judicialized process is of great satisfaction for those who work in the justice sector. In specific cases raised below and whose data are assumptions as to the name of the acc used, victims and witnesses, in order to protect their identity. Has been taken as a core base accuracy and reliability as evidence as fingerprints, it can be determined that fingerprints are unique no two people with the same tracks, so it gives certainty and support research and this It leads to the conviction of those res ponsible for committing crimes. We see that scientific knowledge is predictive based on the laws and theories. For example, the states dactyloscopy fingerprints are unique to that each individ ually, so that finding to mark on the crime scene that constitutes proof the person to whom the mark at some point was there. So in both cases effec tively plated the two defendants are located at the crime scene not only with that of the witnesses but also with scientific support as were the fragments of fingerprints. With this law in a fair based on the conclusions ma de by forensic science applies. The forensic knowledge of actual data that can be observed and verified in great detail. This means that it i s accurate knowledge that should not give rise to doubts. Since no one can be judged by a fact tha t has not been tested in court. Fragments fingerprints were compared with the database of the National Registry of Persons and the National Institute of Foren sic Sciences of Guatemala, specifically the Scientific Technical Department Crime Laboratory Unit of Dactiloscopy . So in the second case described was performed based on the obtained demographic information Automated System Fingerprint Identification Syste m (AFIS) also with the National Institute of Forensic Sciences and the National Registry of Persons (Automated Fingerprint Identification System (AFIS) Past With The National Institute of Forensic Sciences and the National Registry of Persons).