"According to Conti & Vecchiotti only 5 picograms of unidentified biological substance were found (for Stefanoni’s machine they were quasi 10 picograms) however the quantity was judged too little to perform a DNA test.
Yesterday Carlo Torre, made the hypothesis that the substance could be starch. So the whole group moved into the department of histology. They waited for the lab to be available and asked to prepare the reagents for the starch.
It seems that a Lugol Iodine test was performed, and the solution turned dark, which means it was positive for starch carbohydrates. If this is true, in the crevice there was what there was supposed to be for a knife that just had a kitchen use: starch. Therefore they thought the knife was used to cut bread.
But the substance, scanned at the electron-microscope, or maybe just observed with a normal microscope, wouldn't have shown presence of the other types of cells present in the bread. So, it doesn’t come from bread. The hypothesis was advanced that it could be the starch with which the lab gloves are covered.
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Anyway, starch is known for having a highly absorbent power. It would have certainly captured the components of the blood. But, none was detected. Which means, again, that the knife is not the murder weapon."