The morphology of bloodstains presented in criminal scenes is determined, both by blood factors and their characteristics as a fluid, and by external elements such as the mechanism that generates it, the air resistance and the type of surface against which it impacts. The nature of the support can directly affect the appearance of a bloodstain. Therefore, passive spots have been developed on 14 surfaces with diverse and opposite characteristics. In this way we can determine the degree of direct influence exerted on the blood and its morphology. The results prove that the type of surface is key and decisive in the final appearance of each bloodstain, and that their specific characteristics can blur the macula and cause possible mistakes in its interpretation, so it is necessary to emphasize the importance of taking these latest data into consideration to facilitate the development of police investigations when applying the study to a crime scene, improving the understanding of the phenomenon.