Blood is a non-Newtonian fluid responsible for the maintenance of homeostasis in vivo by providing transport of oxygen, carbon dioxide, minerals, and electrolytes, among others, to and from every part of the human body. Plasma, which makes up approximately 55 % of whole blood, is mostly water but does contain some proteins, minerals, and electrolytes while the cellular components, which make up the remaining 45% of whole blood, include erythrocytes (red blood cells; RBC), leukocytes (white blood cells; WBC) and thrombocytes (platelets) . The cellular components and plasma proteins perform specific physiological functions in vivo that are disrupted when the blood leaves the body (ex vivo). Hemoglobin (Hb), an important protein in RBCs that is responsible for the transport of oxygen in the body, consists of two  and two  chains . Each subunit or chain contains a heme group, with a centralized iron atom in a protoporphyrin ring, directly capable of reversibly binding oxygen . Oxygen bound to Hb is referred to as oxyhemoglobin (oxyHb) while Hb without oxygen is referred to as deoxyhemoglobin (deoxyHb) . In vivo, every day roughly 3% of oxyHb is autoxidized to methemoglobin (metHb), a derivative incapable of binding and carrying oxygen . In healthy Hb, such as oxyHb and deoxyHb, iron is present in its ferrous state (Fe 2+ ), compared to the oxidized metHb in which iron is present in its ferric state (Fe 3+ ) . In vivo, internal reduction mechanisms including enzymes glutathione peroxidase and methemoglobin reductase are responsible for maintaining low levels of metHb by converting Hb to its healthy derivatives (1,19). Ex vivo, when blood is deposited, the combination of environmental stressors and loss of the internal reduction mechanisms lead to the accelerated oxidative changes in Hb derivatives . Continued degradation creates further conformational changes to the structure of Hb, leading to the formation of hemichromes (HCs) . The iron in this Hb derivative binds a distal histidine residue rather than oxygen or water . This ex vivo degradation pathway has been of great interest to bloodstain TSD research due to the continuous structural and redox changes in the Hb .