D.C. Code § 16-521: Interrogatories to garnishee; oral examination.

(a)

In any case in which a writ of attachment is issued, the plaintiff may submit interrogatories in writing, in such form as may be allowed by the rules or special order of the court, to be served on any garnishee, asking about any property of the defendant in his possession or charge, or indebtedness of his to the defendant at the time of the service of the attachment, or between the time of service and the filing of his answers to the interrogatories. The garnishee shall file his answers under oath to the interrogatories within ten days after service upon him.

(b)

In addition to the answers to written interrogatories required of him, the garnishee may, on motion, be required to appear in court and be examined orally, under oath, touching any property or credits of the defendant in his hands.