A rock climber who authorities say killed a fellow climber in the Carderock Recreation Area near Potomac was formally indicted Wednesday on a federal voluntary manslaughter charge.

David DiPaolo, 31, of Bristow, Va., was arrested earlier this month in connection with the death of 69-year-old Geoffrey Farrar, who was found bleeding from the head and lying mortally injured at the base of a cliff near the Billy Goat Trail in Montgomery County on Dec. 28.

Word initially spread through the rock-climbing community that Farrar — known to some by the nickname “Carderock Geoff” because he was such a fixture at the recreation area that is part of the Chesapeake and Ohio Canal National Historical Park — had taken a tragic fall.

Federal investigators, however, found his injuries were not consistent with a fall, but instead with blows with blows from a silver-colored claw hammer that was found on the ground nearby.

According to court documents, DiPaolo told police that Farrar tried to choke him at the base of a cliff. Fearing that he was about to lose consciousness, DiPaolo told police, he hit Farrar in the head with the hammer, according to a criminal complaint.

David DiPaolo (Warren County (N.Y.) Sheriff’s Sffice)

DiPaolo’s father, Vincent, has said his son — who met Farrar at Carderock 20 years ago as an 11-year-old interested in climbing — was “no murderer” but would act to defend himself. No lawyer was listed for David DiPaolo in court records Thursday.

DiPaolo had already been charged with manslaughter in connection with the death, and the indictment is merely a formal step to move the case through court. He was scheduled to appear in federal district court in Greenbelt, Md., Thursday, prosecutors said.

Get updates on your area delivered via e-mail