Update: Found!
“They were at the corner of Columbia and Ontario in NW DC when he heard a noise, spooked, and slipped out of his harness.
He is a 2 year old black, white and gray spotted boxer mix. Tail and ears are not docked, 50 pounds, typical white ‘socks’ markings on feet. He was wearing a Royal Blue collar and answers to the name Maurice.
He was lost spotted at 14th and Kenyon.”