Hershey and Chase started with a virus called a blank. They used the radioactive isotope sulfur-35 to label the blank of the virus and phosphorus-32 to label the blank of the virus. They allowed the tagged virus to infect bacteria and studied the results. Hershey and Chase found that the only radioactive isotope within the bacteria was blank. This result indicated that the genetic material inserted by the virus to infect the bacteria was blank.