CHICAGO -- Authorities say the man accused of executing a Chicago 9-year-old last year planned to torture the child by cutting off his fingers and ears.

Cook County State's Attorney Anita Alvarez said at a press conference Tuesday that Tyshawn Lee's murder on Nov. 2 was retaliation for another fatal shooting. She said the suspects blamed the previous incident on a gang they believed Lee's father was in, according to CBS Chicago.

Dwight Boone-Doty CBS Chicago

Dwight Boone-Doty, 22, has been charged with first-degree murder in Lee's death, and the Oct. 18 shooting death of 19-year-old Brianna Jenkins. He has also been charged with attempted murder for allegedly shooting 20-year-old Deshari Bowens in the attack that killed Jenkins.

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Another man, 27-year-old Corey Morgan, also has been charged with first-degree murder in Tyshawn's death; and authorities have issued an arrest warrant for a third suspect, 22-year-old Kevin Edwards.

"These are calculated killers whose actions define the words brutality and cowardice," Acting Chicago Police Supt. John Escalante said.

Boone-Doty allegedly lured Tyshawn away from a basketball court by offering to take him to a store, and then shot him multiple times in an alley.

Prosecutors said Boone-Doty originally planned to kill Lee's grandmother and torture the boy.

"In nearly 30 years of policing, I have never witnessed such a hateful act of treachery and savageness towards an innocent child whose life barely had the chance to flourish," Escalante said.

Corey Morgan Cook County Sheriff

Police and prosecutors said both shootings stemmed from an ongoing gang war between the Terror Dome faction of the Chicago gang the Black P-Stones and the Killa Ward faction of the Gangster Disciples.

Alvarez said that on Oct. 13 that 25-year-old Tracy Morgan was shot and killed while sitting in a car with his mother, who was also wounded in the attack. Morgan's brother, Corey Morgan, planned to retaliate, and allegedly said he "was going to kill grandmas, mothers , and children," Alvarez said.

Corey Morgan, Boone-Doty, and Edwards - all purported Terror Dome members - allegedly went out daily, armed with guns, seeking revenge, Alvarez said.

On Oct. 18, 2015, Boone-Doty allegedly shot Jenkins and Bowens after spotting the duo sitting in car. Alvarez said Boone-Doty and Corey Morgan believed the two victims were rival gang members.

Kevin Edwards Chicago Police Department

She said the suspects were still seeking retaliation when they, and Edwards, spotted Lee playing with a basketball in at a playground. Alvarez said Morgan and Edwards drove off in an SUV while Boone-Doty stayed behind.

Lee put down his basketball and began playing on the swings at the park, and Boone-Doty walked up to him and offered to take him to the store and buy him anything he wanted, Alvarez said. The two then walked into a nearby alley, where Boone-Doty allegedly shot Tyshawn multiple times at close range.

"I don't think I have ever been more disgusted and appalled by such inhumanity. This intentional murder of Tyshawn Lee is among the worst that I have ever seen in my almost 30 years as a prosecutor," Alvarez said.

Authorities said Boone-Doty, who was in custody on unrelated gun charges, gave statements admitting his role in the killings, and said when he shot Tyshawn he "seen that bitch go in his head."

"Shorty, he was like he couldn't take it no more. Shorty couldn't take it no more," Boone-Doty allegedly said, according to Alvarez.

Alvarez said Boone-Doty's initial plan was to torture Tyshawn by kidnapping him, and cutting off his fingers and ears. She also said he set up surveillance of Tyshawn's grandmother at one point, to draw out rival gang members.

Boone-Doty was ordered held without bail at a bond hearing Tuesday afternoon.

Corey Morgan was charged with first-degree murder in Tyshawn's death in November, and is being held without bail.

Edwards remains at large, but a warrant has been issued for his arrest.