Charles County sheriff's investigators said yesterday that they are looking into whether the author of a racist screed distributed anonymously throughout Waldorf on Thanksgiving is affiliated with the Ku Klux Klan or other white extremist group.

Residents went to police on Thursday after someone left 30 copies of racist fliers on community mailboxes in the St. Charles area of Waldorf and under the door at the Lancaster Neighborhood Center.

Several copies of hate letters were found at a post office and church, investigators said.

Addressing "My White Brothers & Sisters of Charles County," the anonymous author invokes "white power." The author urges the killing of blacks--"that means baby's too"--and threatens to bomb the Charles County Courthouse, according to a flier--one of two versions--obtained by The Washington Post.

"No more [racial epithet] in Charles County!!!!!!" the letter says. None of the letters was addressed to a specific individual, authorities said.

Lt. F. Michael Wyant, the commander of the Charles County sheriff's intelligence section, said investigators are looking into whether the wording and distribution tactics used in this case are similar to those used by extremist groups elsewhere. Although the letter writer used the initials "KKK" within the text, it was too early in the investigation to say whether the suspect was a member of the Ku Klux Klan, Wyant said.

"Just because someone writes 'KKK' on a flier doesn't mean that's the case," Wyant said. "We don't know what we've got here."

Wyant said that there are groups in Southern Maryland that claim affiliation with the Klan and that as recently as 1994, Klan members held rallies on the courthouse steps in La Plata. The Southern Poverty Law Center, a civil rights group based in Montgomery, Ala., that compiles state-by-state reports of "hate group" activity, said that six chapters of the Klan were active in Maryland in 1998, none in Southern Maryland.

Two unaddressed copies of fliers were found amid the weekend's collected mail at the U.S. Postal Service distribution center in Waldorf, a postal official said yesterday. Those letters were turned over to the sheriff's office and postal inspectors for examination.

The pastor of Peace Lutheran Church in Waldorf, the Rev. Craig Endicott, found a copy of the flier on the ground near his church on Thanksgiving. He said yesterday that he built his Sunday sermon around it. "Obviously, we have work to do. This is no time to be asleep," he said. "In this county, there's still racial tension."