A lone bomber terrorized the nation for nearly 20 years, planting bombs that killed three Americans and injured many more before his capture in 1996.
www.fbi.gov
And then there's the Unabomber.
IMO all those who wrote letters or sent files, whether to LE or the media, craved the notoriety and that's what compelled them to "brag" about their crimes and to taunt LE with how they were getting away with it. As the Zodiac Killer has.
However, the Unabomber apparently did NOT want to be discovered, but after years and years and years he felt compelled to send his lengthy manifesto to the FBI. There was a debate as to whether or not it should be published, but eventually it was decided to do so, which led to thousands of tips from the public.
One tip was the jackpot---the Unabomber's brother recognized the writing style, and linguistic analysis proved Ted Kaczynzki was the Unabomber.
This lust for attention or making their grievances known often leads to the guilty person.
I can only hope that this murderer gives himself away. So far it doesn't seem like it, but we don't know if LE has received anything of the sort.
I imagine running down every tip, which probably involves tracking down and interviewing every person named, is a very tedious and time-consuming task. That's to say nothing of sorting through literal years worth of DNA in an off-campus student house with an ever-shifting population.
I feel LE is working very diligently and that this doesn't happen as quickly as we would all like.
Jmo