"Tyshawn Lee was murdered in probably the most abhorrent, cowardly, unfathomable crime that I've witnessed in 35 years of policing," Chicago Police Superintendent Garry McCarthy told reporters Thursday.
"We're pretty certain that this is not an accident. He was not a bystander."
The child was targeted, according to McCarthy, because of his "family relationship with a member of a gang."
When asked which family member, he identified the boy's father.
"Tyshawn's father has ties to a certain gang that is in conflict with another gang," McCarthy said.
The father, Pierre Stokes, is not cooperating with police.
He told the Chicago Tribune earlier this week that he thought his son's shooting was deliberate.
"If it wasn't a target, he wouldn't have got hit so many times in the back and the face," said Stokes. "I think he was targeted."
The Chicago newspaper also reported that Stokes disagreed with what police have said about him, but did not talk specifically about whether he belonged to a gang.
McCarthy told reporters investigators believe Tyshawn's death on Monday was the latest in a series of gang-related events that go back as far as August or earlier.
Police are looking for a number of people, he said, not just one person. No arrests have been made in Tyshawn's case.
McCarthy asked anyone with information to step forward. Authorities are offering a $35,000 reward.
The Rev. Michael Pfleger, a priest and local faith leader in Chicago and outspoken advocate against gun violence, offered to pay to relocate any witnesses who feel they would be in danger for providing information.
"What happened to Tyshawn Lee took us to a new low," Pfleger said. "This wasn't a drive-by. This was not a spray of bullets. A baby was executed. A baby was assassinated right behind us in this alley."
"This is a different level," the superintendent said. "These are noncombatants now being assassinated."