On Saturday police charged Rony Alexander Galicia with two counts of first-degree murder and conspiracy to commit murder in connection with the June 5 deaths of 17-year-old Shadi Adi Najjar and 18-year-old Artem S. Ziberov.
The honor roll students were shot to death in Najjar's car in Montgomery Village, just one day shy of their graduation. Police found the car still running when they arrived at the scene.
Galicia, 25, of Germantown, was arrested after DNA found at the scene tied him to the murders. Three other men have previously been arrested.
The killing is said to be in retaliation for a robbery Najjar may have had a part in.