later on, when they found the ryen station wagon in look beach, the first time it was inspected there were no cigarette butts. the second time, they suddenly found two cigarette butts. clearly, they had been taken from the hideout house. >> and there was the blood evidence connecting cooper to the murders. this small speck labeled a-41. a-41 was examined by sheriff's department criminalist daniel gregonis. >> gregonis was a rookie at the time. proper procedure is to do blind testing. you test something and you don't know what the other person's blood is, and you're trying to see whether it's that person or not. but gregonis waited until he had kevin cooper's blood type. >> gregonis originally found a-41 did not match kevin cooper, but then he changed notes to show that it did. >> so, in fact, the testing actually showed that the blood drop was not from somebody with kevin's blood type. >> other evidence prosecutors claim linked cooper to the murders was a bloody footprint on the ryens' bed sheet,