Timothy Krajcir enrolled at Southern Illinois University as a condition of parole after serving time for rape. He graduated in 1981 with a major in administrative justice and a minor in psychology.

His first victim was a classmate, Deborah Shepherd. That crime was eventually solved by DNA comparison, technology that was not available in 1982.

"I've had conversations with him where he's acknowledged that as the science grew, he knew that at some point this day was going to arrive," Lt. Paul Echols of the Carbondale Police Department told CNN.

"He was aware of DNA technology and that he was part of that database -- that someday that he would be matched. He knew it was coming."

In Cape Girardeau, Mo., where Krajcir has admitted killing five women, the killer seemed so aware of police procedures that investigators thought they might be looking for a police officer.