D.C. police are investigating the possibility that the murder of a tourist is linked to two similar attacks in the same neighborhood.

The three incidents all happened within 26 hours of each other, in a 10-block radius in Petworth, said D.C. Police Chief Cathy Lanier. In all three instances, the victims were walking alone.

"It appears that the victims may have been attacked suddenly and without provocation," Lanier said Thursday.

Gary Dederichs, 66, was found in an alley in the 800 block of Emerson Street NW at 6 p.m. Tuesday, with his head resting on a fanny pack. He apparently died of severe head trauma.

Nine hours later, around 3 a.m. Wednesday, a 53-year-old black male was found injured in the roadway of Georgia Avenue NW -- just two blocks away from the scene of the murder.

Initially, police thought this man had been struck by a car, but a medical exam showed that his only injury was blunt force trauma to the head. He remains hospitalized in critical condition.

The third attack happened at 8:40 p.m. Wednesday. A 37-year-old black female was struck in the head by a blunt object at Longfellow and 9th streets NW. That victim is also in the hospital, in serious condition with head trauma.

"It’s been very difficult to get information from the victims due to the nature of their injuries," Lanier said.

The police have not found any connections between the victims -- except they were all alone at the time of the attacks.



"Since all three victims were walking alone, we are asking that residents in the area walk in pairs or groups when possible," Lanier said.

Someone may be coming up behind the victims and hitting them with a hammer or club, NBC4's Pat Collins reported. Neither robbery nor race appears to have been a motive. The victims were of different races.

Dederichs, the man who was killed, was a nurse from Denver. He had been visiting D.C. for about two weeks, and was renting a basement apartment in a house on Illinois Avenue NW.

The entrance to that apartment is in the alley where his body was found.

Police are talking to neighborhood residents, making sure everyone is aware of the situation, and asking them to report anything they may have seen.

"It's terrible, and I'm sorry it happened," a resident said Wednesday. "And I'm sorry it happened in my neighborhood, because we have never had this happen."

Anyone with information about this case is asked to call the police at (202) 727-9099 or submit a tip anonymously by texting 50411.

Stay with NBCWashington.com and NBC4 as the story develops.