When I read stories like this, it makes me truly sad that the physical evidence associated with the Ripper case wasn't better curated and managed over the years - just imagine the amount of fingerprint evidence that there would have been at Dorset Street and the things that we could have learned from well-preserved blood, fingerprints and tissue samples.
Of course, that we don't isn't really anyone's fault - I'm sure that the investigating officers could no more imagine being able to detect what somebody last ate from their fingerprint than they could that we'd someday find ourselves looking at a picture of a man standing on the moon.
Sadly, even if a box of Ripper-related evidence turned up tomorrow, the chain of custody would be so questionable now that any results could easily be dismissed.
Wasn't really thinking of matching actual fingerprints per se, GUT. It was more a comment that advances in technology now allow us to find out what someone last ate, if someone has taken drugs, or used a condom all from their fingerprints.
In the MJK case, given the extent of the damage, there has to be a very good chance that the killer also cut himself during the attack (it's fairly common in sustained attacks for the attacker to injure themselves). If fabrics or other evidence from the crime scene still existed, who knows what we could find out from blood evidence?
With DNA testing now allowing us to find out ethnicity and heritage, we might not be able to say with certainty who the killer WAS, but we could make a decent argument for who it WASN'T.
Of course, it's all a bit of a pipe dream - even if a big box of evidence miraculously turned up tomorrow, contamination would really render any results extremely doubtful (and that's putting it mildly).