So, why’d he quit in the 1980s? No activity since then, or did he get smarter and keep going without being detected?
According to Wiki, he was calling previous victims at least until 2001.
My guess is that they can only tie him to a few of the cases.
“why’d he quit in the 1980s”
Probably DNA technology. If he had been arrested committing a crime then, DNA would go in the database and a match could be made. It was too risky. It was to his benefit to walk the straight and narrow. Just my opinion (as an ID Addict).