Manchas of blood are among the most common traces in crime scenes. Such biological traces, when interpreted within those places, may determine the dynamics of a criminal offence, the identity of a suspect and the time when a crime was committed. Establishing time synce deposition (TSD) of these spots can be the first indication from forensic investigators about when a crime was committed. Such an analysis is very useful when a blood spot is the only piece of evidence available, for example in violent murders. Several methods of analysis have already been proposed in order to address this important issue during the investigation of a crime scene, and this study presents and compares the main methods of analysing the age of a blood spot already reported in literature.