D.C. Mun. Regs. tit. 22, r. 22-B418
Any notice required by this chapter may be served either personally or by certified mail, return receipt requested, directed to the respondent at his or her last known address as shown by the records filed with the Director by the respondent.
If the notice is served personally, it shall be deemed to have been served at the time delivery is made to the respondent.
If the notice is served by certified mail, it shall be deemed to have been served on the date shown on the return receipt showing delivery or refusal of the respondent to receive notice.
In the event the respondent is no longer at the last known address as shown by the records filed with the Director and no forwarding address is available, the notice shall be deemed to have been served on the date the return receipt bearing such notification is received by the Director.
If a respondent scheduled for a hearing does not appear and no continuance has been or is granted, the Director may hear the evidence of those witnesses present, and the Director may proceed to consider the matter and render a decision on the basis of the evidence presented.
D.C. Mun. Regs. tit. 22, r. 22-B418