There are several tests for blood and human blood which are used at crime scenes. The blood was identified as human.
The lack of pcr amplification is part of the mystery , but also part of the validation. If it was a fraud , it would amplify as the DNA of the person it was taken from . There is only one person cited in history presumed to have no paternal DNA. Guess who, That has surprised all the pathologists: samples as good as this normally yield a sequence.
Read the reports and interviews also of such as so called Eucharistic miracle analysis. Impossible to explain or fake. Many pathologists involved not just one. All come to similar conclusion on the pathology. None can explain it or indeed how there are white cells in vitro.