Investigators are probing whether a prominent historian and an associate accused of stealing valuable documents from the Maryland Historical Society also took papers from the National Archives and a handful of other libraries, a prosecutor said in court Tuesday.

The revelation came as a Baltimore City Circuit Judge set bail for Barry H. Landau, 63, at $500,000 and Jason Savedoff, 24, at $750,000. The pair were charged earlier this month with taking 60 historic documents. The papers included some signed by Abraham Lincoln, inaugural ball invitations and a commemoration of the Washington Monument, according to court documents.

On July 9, Landau and Savedoff were arrested after an employee at the Baltimore archive saw Savedoff slip a document in a portfolio and walk out of the library, according to court documents. Police later found 60 documents stashed in Savedoff’s laptop bag in a locker, according to court documents. Landau had signed the documents out, authorities said. A prosecutor said Tuesday the documents had a value of $6 million — a figure defense lawyers said was far too high — and some had come from the National Archives, Connecticut Historical Society and Vassar College. A prosecutor declined to discuss the nature of those documents.

The prosecutor also said Savedoff may have tried to flush some documents down a toilet in a historic society bathroom before his arrest.

“They found little pieces of documents in a toilet,” prosecutor Tracy Varda said.

She also said investigators had uncovered evidence that Landau sold a document taken from the Franklin D. Roosevelt Library in 2010 to a New York memorabilia dealer for $35,000. And a 1780 letter from Benjamin Franklin that belonged to the New York Historical Society turned up in a search of Landau’s New York apartment, Varda said.

So far, prosecutors have only filed charges in the Maryland Historical Society incident. An attorney for Landau disputed those charges.

“There were no documents recovered on Mr. Landau’s person. He was not seen removing documents. There was nothing found in his car,” said Steven D. Silverman. “If the case were tried today based on that evidence, it would be a slam dunk not guilty.”

Savedoff’s attorney has not returned calls for comment.