This is interesting. It sounds to me that LE found something in the case files that pinpointed him. I wonder if they already had interviewed him before and he had some crazy story that they believed the first time.
Then when DNA came to match others they knew he was lying.
Maybe his DNA was identified the first time and he had some crazy excuse about picking up the Kimono garment lying in the street.
I am thinking the kimono was dropped outside away from the attack victims house.
They dont say where it was actually found. So this could be what happened and they didnt have enough to prove it was him if he said he picked it up.
I bet he wore it so victim could not see his face so she could not ID him either.
ETA I think i misread some information so we can scratch my theory because it sounds like they never even tested the DNA until just recently on the Kimono. Not sure why they would not have done that sooner though.
"Her screams caused him to flee and police believe he dropped the stolen kimono as he ran from the home."
"While the DNA link did not give them a name for that person, it did provide detectives with fresh investigative opportunities contained within the pages of the 1988 case file. As a result of re-examining that case, The Saturday Telegraph understands a major breakthrough came within weeks.""
http://www.dailytelegraph.com.au/news/claremont-murders-stolen-silk-gown-key-to-police-making-arrest/news-story/7354e965cc2d7d087d7d207ae1d04d20