JACKSONVILLE, Ill. (AP) _ A former researcher for a project on Abraham Lincoln's early legal career pleaded innocent Tuesday to charges of stealing numerous historic documents.

Sean Brown, 29, is charged with felony theft and tampering with public records at the Morgan County Courthouse. A jury trial was scheduled for May 16.

The former researcher for The Lincoln Papers, a group sponsored by the Illinois Historic Preservation Agency, also faces charges in Sangamon County, where he is scheduled to appear in court Thursday.

In that county, he is accused of stealing $10,000 to $100,000 in documents from the Illinois Regional Archives Depository at the University of Illinois-Springfield.

Prosecutors have said 200 Lincoln documents were stolen from archives in Sangamon, Morgan and Montgomery counties between 1993 and 1996.

An unidentified New York auction house has donated 56 Lincoln documents worth thousands of dollars to Illinois state archivists, said David Blanchette, spokesman for the Illinois Historic Preservation Agency.

Investigators don't yet know if any of the documents are related to the Brown case. None of them are on their search list.

Investigators have recovered 140 of the 200 missing documents.