Is there any known substance that will invalidate DNA typing?
If the DNA is exposed to a nuclease like DNase I or micrococcal nuclease, the DNA will be degraded and unusable. Some chemicals can inhibit PCR; proteases can destroy the polymerase responsible for PCR, or EDTA can chelate the magnesium required for PCR. Various oxidizers can damage DNA (permanganate, hydroxyl radicals, etc) and strong acid can promote the decomposition of nucleotides. Very strong base can also cause hydrolysis of DNA.
