The warrant was reviewed by Assistant State's Attorney Renee Battle-Brooks and was signed by Prince George's Circuit Judge Sherrie Krauser, who is now retired and could not be reached for comment Wednesday.

The warrant return shows police found a .22-caliber revolver with no serial number that was loaded with three rounds, a plastic bag with 15 rounds of .380-caliber ammunition, a "scale with suspected [drug] residue" and drug "packaging material." Police also took two iPads and a MacBook Pro. Police wrote that a firearms target was hanging on the wall and also was taken.

John Erzen, a spokesman for the Prince George's County state's attorney's office, said prosecutors approved the warrant. But he said they later concluded that the information in the search warrant application — which only mentioned that Brown's vehicle was believed to have been involved in a shooting — did not constitute the probable cause needed to search his dorm.

Erzen also noted that city police were looking for a shooting suspect believed to be 5 feet 7 to 5 feet 9 and 135 to 155 pounds. Brown, he said, is about 6 feet and 210 pounds.

Erzen called his office's approval of the warrant a "mistake."

"Just because his vehicle was supposedly at the shooting, that's not enough probable cause to search his residence," Erzen said. "It should not have been signed off on. That's something we dealt with internally."

He said the decision not to pursue the case was "disappointing," given that Brown could have faced charges for illegal possession of a handgun because he was under 21 years old. But Erzen said prosecutors "have a responsibility to be ethical and protect people from prosecution that is unwarranted."

In the Black Guerrilla Family case, 48 alleged gang members and associates were charged in November. Among those charged is Brown's half brother, Wesley Jamal Brown. The Maryland running back's full name is Wesley Jerel Brown.

Connie Dancel, whose family took in Wesley Jerel Brown when he played football at Our Lady of Good Counsel High School, said he did not know his half brother until they met at a family funeral in 2013. She has said Wesley Jerel Brown's troubles stemmed from being in the wrong place at the wrong time.

Police say the shooting occurred outside a birthday party at the Mirage nightclub June 8 for Wesley Jamal Brown and an alleged gang leader named Gerald Johnson. Montel Harvey, 22, has been charged in the BGF case with being the shooter who left the scene in Brown's vehicle.

Attorneys for Wesley Jamal Brown and for Harvey deny the allegations.