There was a lot to link them, all three women were killed the same way. I won’t go into detail.all three had certain items stolen. All three were having their period. All three had their sanitary protection placed rhe same way by the killer.
they think it is possible it is not 1 man, but maybe 1 lady was killed by someone then 18 months later someone else killed the other two ladies
they simply don’t know. But they did catch a petty criminal whose dna showed he was likely related to the killer, but they couldn’t find the person despite a lot of dna testing.
there is also a thought by the police that senior police knew who it was and elected not to take it further, shut it down, for whatever reason,