Robert Hansen
Starting in the 70’s, Hansen abducted 17 women and let them lose in the Alaskan wilderness to be hunted down. Meanwhile, he was a baker in downtown Anchorage, with his wife and kids.
Known as the “Butcher Baker,” he was undone when one of his victims escaped and led the police to his cabin and gave them a description.
After the investigation, it was revealed that he’d assaulted over 30 women, murdered 17 of them, but could only be charged with 4. He ended up dying in prison, while serving a 461 year sentence.
You forgot Harold Shipman, probably the world's most prolific serial killer and a doctor.