(CNN) A federal judge has denied a request to release the name of a suburban Chicago officer who shot dead a security guard earlier this month, according to court records.

Chicago attorney Gregory Kulis, who represents the mother of the slain security guard, Jemel Roberson , filed both a motion and a subpoena on Friday directing the Illinois State Police to release details such as the identity of the Midlothian police officer who fatally shot Roberson and of all witnesses.

Assistant Attorney General Michael C. Stephenson had asked the court to deny the motion, which he said was "an attempt to side-step the basic rules of motion practice, and give the State Police until December 17 to respond to the subpoena. The subpoena required a response by November 30, but that wasn't enough time, he said.

On Tuesday, US District Court Judge Joan Lefkow gave the State Police until December 18 to respond to Kulis' subpoena and set a status hearing for January 8.

Stephenson argued the motion was "in complete disregard" of the federal rule governing subpoenas.