– One of three suspects in the slaying of Tyshawn Lee engaged the 9-year-old in conversation while the boy was on a swing at a playground, then lured him to a nearby alley and gunned him down, Cook County prosecutors and ­Chicago police said Friday.

Judge Peggy Chiampas ordered Corey Morgan held without bail on first-degree murder charges as she shouted at him that she was otherwise unable to protect "grandmothers, mothers and children from you."

"This was a predator grabbing his prey and luring that child into an alley [to be] executed by a close-range gunshot wound," the judge said.

Police Superintendent Garry McCarthy said that a warrant has been issued for the arrest of a second suspect, Kevin Edwards, 22, of Chicago. A third gang member, whom McCarthy did not identify, is in custody on an unrelated charge, he said.

McCarthy said police are still unraveling what roles each of the three played.

But at Morgan's bond hearing, prosecutors said the three members of the Gangster Disciples' Terror Dome faction had been looking for revenge since Morgan's brother was killed and his mother wounded in a shooting on Oct. 13.

Prosecutors alleged that Morgan had vowed to "kill grandmas, mamas, kids and all" after his brother and mother were shot.

On Nov. 2, the three were riding in a black SUV looking for targets when they exited the vehicle and walked into Dawes Park. Tyshawn was playing on a swing set, his basketball next to him, prosecutors said. Morgan and one of the others left in the SUV, while the third gang member picked up Tyshawn's basketball and dribbled it a few times before giving it back to him.

Tyshawn and the individual were seen walking out of the park together. The SUV began following them as the two entered the alley.

When Tyshawn reached about the middle of the alley, the one individual shot him multiple times as the two in the SUV looked on, according to prosecutors and police.

On Friday, McCarthy called the shooting of the 9-year-old "an unfathomable crime."

McCarthy said police believe that at least two killings and other retaliatory shootings over three months led to the decision to target Tyshawn because of his father's gang ties.

Police had questioned Morgan, 27, two days after Tyshawn's killing but released him. Two weeks later, he was arrested again and charged with a weapons violation.

McCarthy said that Tyshawn's father was "not at all a help" to police in the investigation of his son's killing. The autopsy report showed the bullets struck the boy in his thumb and hand and grazed his back. The fatal shot hit him in the head.