From the NYT story:

When the issue surfaced last year, Mr. Berger insisted that he had removed the classified material inadvertently. But in the plea agreement reached with prosecutors, he is expected to admit that he intentionally removed copies of five classified documents, destroyed three and misled staff members at the National Archives when confronted about it, according to an associate of Mr. Berger’s who is involved in his defense but who spoke on the condition of anonymity because the plea has not been formalized in court.