PORTLAND - Investigators are tracing the routes of a long-haul trucker charged with killing two prostitutes to determine his connection to the deaths of 20 or more other young women who frequented truck stops.

Detectives in Oregon began checking out the trucker after they were notified he was a suspect in an assault rape in the Seattle area.

Scott William Cox, 28, drove his rig from British Columbia to Mexico, from the West Coast to Ohio, staying in Newberg, about 20 miles out of Portland, when he wasn't on the road.

Cox was in cities where 20 strikingly similar crimes occurred, said detectives, who refused to elaborate on similarities or identify the cities.

Police in several states are looking over their files of unsolved slayings, Newberg Police Chief David Bishop said.

The Washington state attorney general's office has offered to serve as a clearinghouse for police agencies investigating Cox.

"This is just the beginning," Bishop said after a meeting Dec. 19 in Seattle with investigators from Oregon, Washington, California and British Columbia.

"During the meeting, as each agency shared information about murder cases in its area, it became obvious that many similarities exist in the method and profile of murders," Bishop said.

Police in Newberg received more than 200 responses from police agencies after relaying information about Cox.

"We have continued being contacted by other agencies and we're sending out information hot and heavy all over the West Coast and back to the Midwest," said Newberg police Detective Ken Summers.

Cox is charged with killing prostitutes Reena Brunson, 34, on Nov. 24, 1990, and Victoria Rhone, 32, on Feb. 19, 1991. Brunson was stabbed; Rhone was strangled. Both bodies were found in Portland.

Newberg police launched their investigation in early August after they were told Cox was a suspect in a Seattle assault-rape on Memorial Day weekend.

In November, Cox was convicted of gun theft in Medford in southern Oregon. He's serving a six-month sentence in the Yamhill County Jail in McMinnville.

Records police obtained from his employer, Schoene Trucking, document travels by Cox across the country dating back to 1983.

"He fits a real potential to go up and down the I-5 corridor and get away with it," said District Attorney Douglas M. McGeary in Medford.

DNA tests on blood and hair found on the two women "absolutely, positively" linked Cox to both Portland slayings, police said.

In an affidavit filed Oct. 22, police Officer Thomas Perritt said Cox reportedly told a former girlfriend he killed Brunson.

"In November of 1990, Mr. Cox told (her) that he had just knifed a prostitute in his pickup truck for not doing what he wanted her to do," the affidavit said.

Perritt wrote that Cox had a bloodstained sweater and usually carried a hunting knife. Police seized both items.

Cox also faces a forgery charge in Olympia. His attorney, Eric Hanson, said an extradition warrant was served and Cox will face charges in Washington after the Oregon charges are resolved.

A judge entered a not guilty plea for Cox to the two Portland murder charges. A trial date will be set during a Jan. 23 hearing, Hanson said.

Charges haven't been filed in the Seattle area rape case because the victim hasn't been found, said Dan Donohoe, spokesman for the King County prosecutor's office.