SILVER SPRING, MD -- The shooting death of a 27-year-old man by a licensed, armed security guard on Sept. 23 remains under investigation by Montgomery County police and prosecutors who have not yet determined if the shooting was justified.

The victim's family said they have been waiting too long to find out.

"We have yet to gain any sort of information," said Nigel Holder, the uncle of victim Deon Christopher McDonald.

"We're still trying to find out how this young man goes into a 7-Eleven and is shot in the back of the head. To us, it just makes absolutely no sense," Holder said.

RELATED: Man killed by 7-Eleven security guard after altercation

The shooting happened just before 4 a.m. on September 23rd outside the 7-Eleven at 8202 Georgia Ave. in Silver Spring, Md.

Video of the aftermath shows the guard with his handgun holstered reporting the incident to 9-1-1, pacing in front of the store where McDonald lay on the ground.

McDonald was not armed and his right arm was in a cast and sling after a previous injury, his uncle said.

Police and prosecutors said there are multiple security camera videos that show at least some of the events.

However, there are potential witnesses who have not yet made themselves available for interviews and final toxicology reports from the Maryland Medical Examiner's officer are not complete, according to sources familiar with the investigation.

Police plan to meet with prosecutors in as soon as a week to discuss the case, according to Captain Paul Starks, spokesman for Montgomery County police.

Starks called the matter an "active investigation."

Police released the following statement at the time of the shooting:

"McDonald was purchasing an item inside the 7-Eleven and became involved in a dispute with the store clerk. An armed, on-duty security guard intervened. The dispute between McDonald and the security guard became physical and continued to the outside of the store. During the physical altercation outside of the store, the 44-year-old security guard discharged his weapon and struck McDonald."

McDonald's family said he did not have a weapon and he was shot in the back of the head.

The security guard is a licensed private investigator with a valid permit to wear and carry a handgun in Maryland, according to authorities.

The permits are issued by the Maryland State Police. The minimum training to qualify for such permits is 16 hours.