Woah

Yeah after 11 years

I meant they could have done the same thing years before.

Isn't it because the culprit committed the last 2 crimes with the intention to get caught? And that's how the investigators made the connection. Remember he was using aliases and his relationships with the victims in the past were hidden. Whereas he did not bother to do all that on his latest crimes because he wanted to get caught by Sakuma.

Well it isn't uncommon for cases to go cold or unsolved for years. 11 years ago they might not have had the resources they have now. Also, if he was using alias that makes it more difficult to establish connections between the victims since he was working as a counselor there patient confidentiality so know one would know the connection of all the victims struggling with their sexuality and since there were no witnesses other than Sakuma they didn't even know what the killer looked like. Basically they only caught him now because he let himself be caught.

Ah, thank you.
I was curious because it wasn't completely explained how the culprit hid from the police so I assumed the detectives were idiots and not that the murderer was a mastermind, haha ╮(￣▽￣)╭