Torres' attorney said his client had been receiving psychiatric treatment.
Dealers found to be in possession of stolen books have cooperated with authorities and returned the books to Harvard, according to the district attorney's office.
Before Torres' arrest, one of the stolen books was allegedly sold for $2,400 in Grenada and then allegedly re-sold for $4,800 in London.
Torres, who has no affiliation with the University, was granted library privileges because his wife is a Harvard graduate student, Mederos said.
A Widener library official confirmed last month that it is the library's policy to grant library privileges to the spouses of students and faculty members.
Torres' wife has not been implicated in the investigation, Mederos said.
--The Associated Press contributed to the reporting of this story.