1)A thief breaks a window of a car parked in a shopping center
and steals a purse that was left on the car’s front seat. You are a
forensic detective called to the crime scene. You discover that the
thief cut himself or herself on the broken window glass. You test a
sample o blood left behind by the thief. It is O+. A suspect with a
cut forearm is arrested behind a restaurant just 3 blocks from the
car. You take a sample of the suspect’s blood and mix it with
Anti-A. You immediately know that the suspect is not the person who
cut himself on the broken car window. How do you know this?

2). You are called to take a statement from an elderly man who
is dying of lung cancer. he claims that as a young man, he was
involved in a bank robbery about 30years ago, which ended in a
shoot-out with oilice. You do some research and discover that there
was a bank robbery fitting this description about 30 years ago. The
report states that although the poilice did shoot the suspect and
wound him, he escaped. the blood from the crime scene was B-. You
decide to take a blood sample from the man. You take a blood from
the elderly man and mix it with anti-A and it agglutinates. Was the
elderly man telling the truth? How do you know?