Contrary to the jury instructions.
That troubled me too so I dug up the directions and read this a number of times
FURTHER, EACH FACT WHICH IS ESSENTIAL TO COMPLETE A SET OF CIRCUMSTANCES NECESSARY TO ESTABLISH THE DEFENDANT'S GUILT MUST BE PROVED BEYOND A REASONABLE DOUBT. IN OTHER WORDS, BEFORE AN INFERENCE ESSENTIAL TO ESTABLISH GUILT MAY BE FOUND TO HAVE BEEN PROVED BEYOND A REASONABLE DOUBT, EACH FACT OR CIRCUMSTANCES UPON WHICH THE INFERENCE NECESSARILY RESTS MUST BE PROVED BEYOND A REASONABLE DOUBT.
The way I can reconcile the prosecutor and the above is that the facts themselves (ie existance of blood, hair, fibers etc) each have to be established beyond a reasonable doubt and then the inferences drawn from them would be considered in total. So, in the instant case we would first acknowledge that each piece of evidence exists without drawing infernences and then when that step is done go to the step of drawing an inference from all of the evidence not just bits of it.