Seven shots broke the silence in the Chicago alley where 9-year-old Tyshawn Lee, who had been playing basketball in a park nearby, had just been lured. As the first pop exploded from the .40-caliber handgun’s barrel, the little boy raised his hands to cover his face.

The man who killed him, prosecutors say, later boasted in a recorded jailhouse conversation that he found it funny.

“I’m looking at him. We walking. Bop,” Dwright Boone-Doty said, recounting the November 2015 killing in a tape played during his murder trial this week. “Hit the ground. Bop-bop-bop-bop-bop. I’m laughing.”

Tyshawn’s killing horrified Chicago, which has long endured gun violence and gang conflict. Prosecutors spent nearly three weeks presenting evidence against Boone-Doty, 25, and his co-defendant Corey Morgan, 31, before resting their case on Wednesday. They argue that the execution-style killing, motivated by gang rivalries, was part of a revenge plot for a shooting that killed Morgan’s brother and injured his mother. To prove its case, the state’s attorney has used novel DNA evidence, jailhouse recordings and testimony from a close family friend to paint the alleged killers as callous and calculating.

“Tyshawn brought a basketball to Dawes Park. Corey Morgan, Dwright Doty and Kevin Edwards brought guns,” Assistant State’s Attorney Margaret Hillmann told jurors, also naming Edwards, who has pleaded guilty to driving a getaway vehicle. “And Dwright Doty took out a .40-caliber handgun, and he executed Tyshawn in broad daylight.”

Morgan’s defense attorney has argued that Boone-Doty, who is accused of pulling the trigger, acted alone. Boone-Doty’s defense, meanwhile, has questioned the DNA evidence and suggested he was lying in the jailhouse tapes to impress another inmate.

On Nov. 2, 2015, police say, Tyshawn was playing on the Dawes Park basketball court on the city’s South Side when he was led into an alley outside of anyone’s view and then shot seven times.

“It was one of the most evil things I’ve ever seen,” the Rev. Michael Pfleger, the priest who later presided over Tyshawn’s funeral, told the Associated Press. “I was over there and to see a young boy laying in an alley next to a garbage can with his basketball a few feet away, this assassination of a 9-year-old child took violence in Chicago to a new low.”

One bullet tore through the boy’s thumb and shattered, nearly severing the finger and shooting shell fragments into Tyshawn’s face. Tyshawn’s palm was close enough to the barrel for the ignited gun powder to burn his skin, Cook County Medical Examiner Ponni Arunkumar later testified. Two more bullets pierced his right hand. The fatal blow hit the boy’s temple, piercing his brain and exiting through the other side of his head, Arunkumar said.

For weeks after Tyshawn’s body was found, police hit a dead end. No one had seen the shooting. Investigators didn’t know why the boy had been targeted. A cash reward for information in the case grew to more than $10,000.

“Break the code of silence,” a reward poster on a memorial erected at the site of the murder read. “Speak for me!”

Eventually, several teenage witnesses told police they had seen Boone-Doty, Morgan and Edwards near the park before the shooting. Police developed a theory: The three men belonged to the Bang Bang Gang/Terror Dome faction of the Black P Stones and plotted to murder the 9-year-old to send a message to the boy’s father, who allegedly belonged to a rival gang, the Killa Ward faction Gangster Disciples. Other members of the Gangster Disciples had shot Morgan’s mother and killed his brother in October 2015.

But since no one witnessed the shooting and little physical evidence connected Boone-Doty to the crime scene, police and prosecutors had a difficult challenge in charging him — until a scientist agreed to use a controversial, cutting-edge DNA technique called “probabilistic genotyping” for the first time in Illinois. The geneticist said the method, which uses an algorithm to model and identify DNA profiles, was able to connect mixed and damaged DNA samples collected from Tyshawn’s basketball to Boone-Doty.

Prosecutors charged Morgan and Edwards with murder four weeks after the slaying but waited until March 2016 to charge Boone-Doty after a grand jury voted to indict him. Prosecutors allege Morgan and Edwards helped plot the killing and drove Boone-Doty to and from the crime scene.

When the trial began Sept. 17, prosecutors introduced the jailhouse recordings, which were taped for authorities by an unlikely source: a hardened gang leader.

Demetrius Murray, then second-in-command within a faction of the Gangster Disciples, had recently been convicted of a shooting and sentenced to 10 years in prison in the same facility where Boone-Doty was held. Around January 2016, he agreed to wear a recorder, hoping he might get out early for his cooperation. But he had another motive as well, he told the court on Monday.

“My other motivation was that, like, a person that brags about things like that, it don’t add up to me,” he testified. “It ain’t right.”

Boone-Doty told Murray in one recording that he had planned to kidnap Tyshawn and torture the boy by cutting off all of his fingers.

“You ain’t never stepped back and thought, damn, I shouldn’t have did that?” Murray asked Boone-Doty, the Chicago Tribune reported.

“No, I don’t got that in my head, not even a little bit,” Boone-Doty answered.

He also bragged on tape about watching the gunfire fatally hit the 9-year-old boy.

“I hit shorty like 12 times,” Boone-Doty told the high-ranking gang member in jail, the Sun-Times reported. “He so little. The [bullets] are coming out. I see that b---- go in his head. Boom! That b---- came out, right here, like.”

In court, Boone-Doty’s attorneys suggested their client was trying to look tough in Murray’s eyes. “People say a lot of things, don’t they?”Assistant Public Defender Danita Ivory asked Murray on cross-examination, the Sun-Times reported.

His lawyers also questioned whether the state can prove he was the man who pulled the trigger and pointed out that the forensic expert who did the DNA tests had doubts about using the technique in this case.

“I was convinced by people expressing to me the importance of this case and the need for me to ‘man up,’ ” said John Buckleton, the co-creator of the DNA-testing technique called STRmix, during a cross-examination.

“Was there a lot of pressure to solve this case?” Assistant Public Defender Michael Buresh asked Buckleton on Sept. 24, the Sun-Times reported.

“I believe it was considered important and they were prepared to invest resources,” he answered.

Despite his apparent hesitancy, Buckleton told the court the DNA match gave “very strong support” to the prosecution’s claim that Boone-Doty had held the basketball.

Closing arguments are scheduled Thursday before two separate juries begin deliberations over the charges against Boone-Doty and Morgan.

Edwards, who police said drove the SUV used to stalk Tyshawn and flee after the shooting, pleaded guilty to first-degree murder and was sentenced to 25 years in prison last month, the Associated Press reported.