This accident happened November 11th 1977. It was a Piper PA-23... departed from Columbus OH en roue to Dulles when it crashed into what has been recorded on record as a "townhouse" at 2:12pm. Only a single fatality is listed (ground fatalities are typically accounted for in the totals), so I'm not so sure on the accuracy of the rest of the story. Must have been a late lunch. I searched the Washington Post archives and didn't find any related news stories. What other papers existed around here at the time?
http://aviation-safety.net/wikibase/wiki.php?id=11881