Investigators in several states, including Pennsylvania and New Jersey, are looking at unsolved murder cases from the late 1970s and early 1980s to determine whether confessed killer Timothy Krajcir could have been involved, authorities said yesterday.

Krajcir, 63, a native of Allentown, pleaded guilty Monday to the 1982 rape and murder of Southern Illinois University student Deborah Sheppard. Later Monday, he was charged in Cape Girardeau, Mo., with killing five women from 1977 to 1982. Authorities also announced that day that Krajcir admitted to three other killings.

The locations of those killings were not released, but police in Reading; Marion, Ill.; and Paducah, Ky., are taking a close look at Krajcir. Meanwhile, authorities in Poplar Bluff, Mo., and New York, New Jersey and Colorado are reviewing unsolved cases to see if there is a possible link.

Krajcir has spent most of his adult life behind bars for sex crimes. After a stint with the Navy, he entered the Illinois prison system in 1963 on rape charges. Except for a brief period of freedom in the late 1970s and early 1980s, Krajcir has been in prison ever since. Records show that he was arrested in Allentown in 1983 on sexual-assault charges and served time in prison in Pennsylvania, the Allentown Morning Call reported this week.

DNA evidence connected Krajcir to the Sheppard killing in Carbondale, Ill., and the Cape Girardeau murders. Authorities in Pennsylvania said DNA evidence also links him to the 1979 murder of 51-year-old Myrtle Rupp, found strangled inside her Reading home.

DNA collected from the murder scene was submitted to a nationwide database and Krajcir came up as a match, Pennsylvania State Police Lt. Thomas G. McDaniel said.

"We feel pretty confident in the investigation," McDaniel said. Authorities were investigating whether Krajcir could have been involved in other unsolved crimes in Pennsylvania.

Smith said Krajcir agreed to admit to the killings in Cape Girardeau and Carbondale only after authorities promised not to pursue the death penalty. Smith said it is possible Krajcir killed others in addition to the ones he's admitted to, but he doubted it.

"He disclosed some things he wasn't really forced to up front," Smith said. "On the other hand, could he have done others? Yes."