To be fair, it's not like they caught him. He killed himself.
The stalker was the source of many a relief twist for me.
At first I was like, "Oh no, his twin sister is the stalker. He musta killed himself right after killing the doctor to make all this happen." But then, no.
And then I was like, "Oh no, their father is the stalker." But then, no.
I'm a little annoyed that they're holding off on revealing the identities of the twins to each other. Seems like something they would have EVENTUALLY talked about by the time they were teenagers.