Federal prosecutors trying former Allegheny County Coroner Dr. Cyril H. Wecht contend that he has engaged in a "practice of threatening potential witnesses," and in a recent court filing they cited two letters he wrote to a potential witness against him in which he quotes a poem about the extermination of Jews.

Dr. Wecht's defense lawyers characterized the letters as part of a long-running exchange between the two men and called the government's allegations a "pathetic attempt to smear" their client.

The prosecution's claims were contained in a brief filed by Assistant U.S. Attorney Stephen S. Stallings yesterday in response to an order by U.S. District Judge Arthur J. Schwab that the jury in Dr. Wecht's case remain anonymous.

While asserting a fear of possible threats, the government had not sought an anonymous jury. Judge Schwab issued that order on his own and has not given an explanation for it. The defense has strenuously objected to an anonymous jury.

In yesterday's brief, Mr. Stallings said he could understand why the judge would issue such an order, given both the "significant, persistent media coverage" of the case and allegations of threats by Dr. Wecht and "those aligned with him."

In his brief, Mr. Stallings quoted two letters written by Dr. Wecht, 76, to Gerald Schiller, 69, of Penn Hills.

The letters between the two men started in 2004 after Dr. Wecht had a letter to the editor published in the Pittsburgh Tribune-Review, claiming that Yasser Arafat died from AIDS.

After Mr. Schiller wrote a letter to the editor in response, Dr. Wecht sent a personal letter to his home.

The two men have exchanged several letters since, including one sent by Dr. Wecht to Mr. Schiller and his wife on Sept. 24 in which he congratulated them for having letters to the editor published in both local newspapers on the same day.

"And with such precise timing. I haven't witnessed anything like that since the Nazis utilized their panzer divisions to overrun much of Western Europe and kill millions of innocent people in World War II," Dr. Wecht wrote. He then recited a poem dedicated to both of them:

What makes your bavarian garden bloom so well?

If you tell me the truth, I promise not to tell.

Presumably, ample fertilizer is the underlying basis.

Would using exterminated Jews be considered too racist?

Mr. Schiller, a retired chemist, never worked in the coroner's office and is not directly involved in any of the matters that led to Dr. Wecht's indictment.

Defense attorney Jerry McDevitt said that the only involvement this "alleged witness has is that the two of them have been involved in a colorful letter writing campaign to each other and to newspaper editors regarding various issues of the day, with both trading creative insults with each other."

Mr. Schiller characterized it differently, saying he did feel threatened by Dr. Wecht's letters.

"There's nothing funny about this whole matter," he said. "I didn't see anything lighthearted in any of Dr. Wecht's letters. It's a little far removed from a friendly feud. He's obviously researched me, my wife."

In his court filing, Mr. Stallings also cited a handwritten note left for a receptionist at the coroner's office the day she was scheduled to testify before the grand jury in the Wecht case, in which she was called a "snitch." The note was left by the solicitor of the office, he said.

"But the real threat posed by defendant, of course, is not physical, but that he would undertake financially costly legal action against those involved in the judicial process," the prosecutor wrote.

After he was charged in a criminal proceeding in 1980, Mr. Stallings continued, Dr. Wecht filed lawsuits against the district attorney, four assistant prosecutors, the judge and the grand jury that returned the charges against him.

"[It] is certainly reasonable for the court in this case to seek to provide a modicum of protection from threats and harassment, both from the media and the defendant," to jurors in the trial, he wrote.

"Cyril Wecht has never had any reason to sue jurors because they've always acquitted him," Mr. McDevitt said. "Having the government suggest anything to the contrary is just another silly act of desperation."