Officers responded to a home in the 6300 block of Red Haven Road shortly after 3 a.m. on Monday, Feb. 24, after reports of gunfire.
When they arrived, police found DiAngelo Smith, 33, sitting in a vehicle outside the residence with a gun, investigators said.
He was taken into custody without incident.
Inside the home, officers discovered his grandparents, Jack Dee Stokes, 78, and Barbara Strokes, 65, dead.
Police say that detectives believe that Smith was residing at the residence with his grandparents. The motive remains unclear.
It was the second double shooting in Howard County over the weekend.
Investigators quickly learned that the suspect and the victims were relatives. According to police, the suspect shot both victims before retreating to his car.
The identities of those involved have not yet been released.
Smith was charged with two counts of first-degree murder and other related offenses. He is being held without bail at the Howard County Detention Center.
Stay with Daily Voice for updates.
Want breaking news in the DMV as it happens? Join the DMV All Incidents Facebook group.
Click here to follow Daily Voice Indian Head-Nanjemoy and receive free news updates.