Four teenagers were killed in a multiple shooting on South Capital Street in southeast D.C. on March 30, 2010.
Five people are facing additional charges in connection with shootings in the District of Columbia that left four dead last year.
A Superior Court grand jury on Wednesday returned a 54-count superseding indictment that includes charges of murder, theft, conspiracy, armed robbery and assorted other crimes. The indictment adds 30 new counts against five D.C. men who were indicted last December and who remain in custody.
The charges relate to five murders and nine non-fatal shootings in what prosecutors say was a week of related killings involving teenagers and young men last year. The spasm of violence culminated in shootings on March 30, 2010, that killed four people and injured six others.
U.S. Attorney Ron Machen says the investigation continues and more charges are possible.