A key biomacromolecule in the growing area of liquid biopsies, cfDNA could provide non-invasive and safer screening procedures to assess fetal health, detect the early stages of various cancers and rejection of transplants. Found in various bodily fluids including serum, plasma, saliva, cerebral spinal fluid (CSF), and urine, cfDNA can be isolated from individuals in both healthy and various disease states. In healthy individuals, cfDNA is actively secreted from cells as DNA is continually synthesized by cell turn over through apoptosis. cfDNA associated with disease states is released due to different types of cell death such as apoptosis, necrosis, autophagy, or mitotic catastrophe. Apoptosis activates endogenous endonucleases that cleave DNA in repeatable lengths. DNA is wrapped around nucleosomes like "beads on a string". The pattern of cfDNA cleavage is guided by the nucleosome positioning. Variations of 165 bp cfDNA lengths and multiples thereof are a result of the length of DNA wrapped around the nucleosome, the different DNA linker lengths between the nucleosomes, and degradation of the linkers between the nucleosomes.