Just days after Reginald Jackson opened fire at four men sitting on a stoop in the Austin neighborhood in 2014, one victim identified him on Facebook, Cook County prosecutors said.

And then last year, another victim identified Jackson as one of the three gunman who wounded him and his friends on June 4, 2014, prosecutors said.

But the 27-year-old wasn’t arrested until this month, prompting Judge Maria Kuriakos-Ciesil on Wednesday to ask why it took so long to charge him.

Assistant State’s Attorney Guy Lisuzzo said the investigation was ongoing, and that more witnesses were interviewed as the case progressed.

Still, Kuriakos-Ciesil was perplexed why it took 2 1/2 years even though Jackson was allegedly identified and then stopped in a vehicle four days after the shooting with two of the three handguns prosecutors say were most likely used in the crime.

Jackson’s attorney called the identification of her client “suspect” and said he was buying gas and walking to the vehicle when the weapons were recovered.

Killed in the shooting was 18-year-old Ronald Holliman.

Ronald Holliman

Holliman was shot in the right knee, left buttocks and left thigh when Jackson and two others came from an alley and began firing at them in the 4900 block of West End Avenue, Assistant State’s Attorney Sheila York said.

One victim, a 21-year-old man, fell down after he was shot in the left arm, left leg, back, abdomen and flank, York said. When that man looked up, he saw a gunman pointing a gun over him, so he covered up on the ground.

But then he heard a loud sound like a failing transmission. He looked up and saw a gray van driving away westbound on West End, York said.

That victim eventually saw three men jump out of the van at a nearby intersection and run away, York said.

Another man, then 26, was shot in the chest, back, abdomen and flank, York said.

A 17-year-old suffered a graze wound to his right hip, York said.

Based on the shell casings and fired bullets, two 9 mm handguns and a .45-caliber pistol were used in the shootings, York said.

Two 9 mm handguns were found in the car Jackson was in on June 8, 2014, York said.

Preliminary tests show those two guns were used in Holliman’s murder, York said.

Jackson, who has a pending weapons case, is charged with murder and three counts of attempted murder.

Kuriakos-Ciesil ordered Jackson, of the 700 block of West 50th, held on $600,000 bail.

No information was available Wednesday about whether the other gunman have been charged.