1. In 1972, before DNA technology existed, a robbery occurred at 2:00 AM at a store. The thief was cut on a piece of broken glass during the break-in. A forensic team collected and tested a
sample of blood left behind by the thief. It was O-. The police brought in a suspect with a cut
forearm who was arrested several blocks from the store, and who resembles someone seen
leaving the store at the time of the robbery. A sample of the suspect's blood was taken and
tested for blood type. When the suspect's blood was mixed with anti-A serum, it was
immediately clear that the suspect was not the person who committed the robbery. Explain
how the test indicated this fact?