So, accused was pulled over and was found with a knife which in turn had human blood sample of A positive ( common in 1/3 of humans) which happen to match 1 of the victims. Blood type of victim number 2 must have different as there has been been no reporting of the fact that as to why there wasn't a second blood type found on the knife. I find this quite peculiar. Maybe the knife found in question in the boot of the car isn't the murder weapon at all. The suspects alibi could have been seen as plausible back 47 years ago, hence he wasn't charged .