Police are investigating whether notes left at a truck-stop ministry could offer clues in the effort to determine who killed seven women, most of them prostitutes.

The notes, found at an Oklahoma City truck stop where one of the victims was last seen, rail against prostitution. One refers to "parking lot sin," and a second note, dated Jan. 31, reads: "Hey Minister, You Need to Get busy for Jesus AND Clear The Whores Out of Here." It was signed, "WARNING."

The notes were discovered by Barry McLead, who runs a ministry out of a converted horse trailer at the northeastern Oklahoma City truck stop.

Shortly before McLead discovered the notes, the body of Casey Jo Pipestem was found in a creek near Grapevine, Texas. Police investigating her death have asked for copies of the notes.

Investigators believe the women may have been murdered by the same person but have been unable to confirm that theory. Their bodies were dumped along highways or near creeks in Oklahoma, Arkansas, Texas and Mississippi.

More than 60 investigators from six states and 17 agencies met in Oklahoma City on Friday to compare clues on the slayings.

The victims' bodies were discovered between July and January. Six were prostitutes; the seventh has not been identified. Four were from the Oklahoma City area. At least four were last seen at truck stops, and at least three were strangled. Most of the bodies were nude.