How does the classification of blood type help in CSI?

How does the classification of blood type help in CSI?

Richard Saferstein (Former Chief Forensic Scientist) gives expert video advice on: What is blood made of?; How does the classification of blood type help in CSI?; Why are blood stains studied in CSI? and more...

Blood typing today doesn't help a forensic scientist. It used to, but when DNA analysis came along in the 1980s, it quickly supplanted the traditional blood type ABO test for the analysis of crime scene blood stains. So today, blood typing is more of a historical note than anything else. It is very unusual, probably non existent, to hear of anybody typing blood for its ABO content in a forensic situation.