The way Prince George’s County police tell it, the 6-year-old boy found the loaded revolver in a Spider-Man backpack that was lying on the floor of the home where he stayed with his great-grandmother. Raymond A. Brown, police say, was responsible for the weapon being there.

Brown, 20, was charged Tuesday with reckless endangerment and allowing access to and possession of a firearm by a minor — all misdemeanor counts stemming from the boy’s death Monday. The 6-year-old, a first-grader, pulled the gun from the backpack about 2:40 p.m. and accidentally shot himself in the chest, police said.

Brown stayed in the home on Arbutus Lane in Clinton where the incident occurred, though he apparently had no family ties to the boy or the great-grandmother, police said. Brown was not there when the accident occurred, but he returned a short time later and was taken into police custody, authorities said.

Police have said the boy’s great-grandmother and grandmother were home when the shooting occurred, as were two girls, ages 9 and 11, who also are relatives. Julie Parker, a Prince George’s police spokeswoman, said detectives believe that Brown was responsible for both bringing the gun into the home and putting it in the backpack, though they are still trying to determine who owned the gun and how it came into Brown’s possession.

Police revealed few other details of the case. Parker said she was not sure to whom the backpack belonged or where in the home the shooting occurred.

And Parker took the unusual step Tuesday of saying police would not release the 6-year-old’s name because he is young and the victim of a crime.

“It’s just something we’ve elected not to do,” Parker said.

The department — like most major departments across the country — routinely releases identities of those killed in homicides and car crashes, including victims who are younger than 18.

Authorities said Brown was ordered held on $45,000 bond.

Two women standing outside the home where the shooting occurred declined to talk to a reporter Tuesday morning. Attempts to reach Brown’s relatives were unsuccessful.

Staff researcher Magda Jean-Louis contributed to this report.