“I request to interview you as soon as possible about your comments about Sergeant Bergdahl during frequent appearances in front of large audiences in advance of his court-martial," said the letter, which was obtained Saturday. "Based on your personal knowledge of matters that are relevant to Sergeant Bergdahl’s right to a fair trial this interview will help us determine whether to seek a deposition order under Rule of Court-Martial 702 or your personal appearance as a witness at an Article 39(a) session of the court-martial.”