FORT MEADE, Md. — An Army private accused of sending reams of classified US documents to the secret-spilling website WikiLeaks was kept in tight pretrial confinement partly because another prisoner had recently committed suicide, the former security chief at the Quantico, Va., Marine Corps base testified Wednesday.

Marine Colonel Robert Oltman appeared as a witness on the second day of a pretrial hearing for Private First Class Bradley Manning, who is seeking dismissal of all charges, claiming his confinement in the Quantico brig amounted to illegal punishment.