Explain the two key properties of blood that allow it to be a key piece of evidence

The two key properties of blood that allow it to be a key piece of evidence are: Blood is cohesive (behaves in a certain way when it hits a surface) and Blood travels in spherical drops (surface tension). The blood is common in the violent crimes like the murder, homicide, sexual crimes, between others. Usually found in the used weapon. Across a drop blood can decide: the DNA pathological diseases, blood group between others.