That was Dennis Rader, aka BTK. He was active from 1974 to 1979, then took a break, which it looks like he was doing at the end of the series. He killed a couple more in the mid eighties, and then one more in 91. He probably would have got away with the murders, but just had to taunt the police in the mid 2000s. He communicated a few times and then asked them if a floppy disk could be traced. They told him it couldn't so the silly twat sent it in and got caught.
So, unless there's a big time jump, we've seen the last of him for a while.
https://en.wikipedia.org/wiki/Dennis_RaderIf the next series is set from 79-81 or so, series 3 or 4 will probably be The Night Stalker. His capture was fucking nuts.
https://en.wikipedia.org/wiki/Richard_Ramirez#CaptureFor one similar to BTK, ie just a scene here and there, Dahmer would be a good choice, as he was active starting in 1978, ending in 1991.