. >> 24-year-old jason sabidove walked out of federal court. >> do you feel relieved today with a guilty verdict? >> we're not going to say anything. >> reporter: sabidove admitted he conspired with barry landau to steal hundreds of documents. dozens were swiped from here at the maryland historical society, including a document signed by president lincoln, worth $300,000. in july, this is where the duo was arrested. today, while he wasn't talking about his plea, barry landau's attorney was. steve silverman says landau was upset because his supposed friend is pinning the entire scheme on him. but he says the evidence shows otherwise. >> all of the documents were under the custody and control of jason sabidove. >> reporter: this is why museums are constantly updating and changing their security. >> reporter: paul brackoff says thefts are thoroughly investigated. >> unless you're going to do full body searches and be very invasive, there are going to be able to beat you and stillsteal documents. >> reporter: landau, a historian has largely been portrayed as the mastermind of the heist, some