CHICAGO » A 9-year-old Chicago boy who was fatally shot this week was "lured" from a park into an alley and executed because of his father’s alleged gang connections, police Superintendent Garry McCarthy said today in a crime he described as among the most "unfathomable" of his 35 years in policing.

Tyshawn Lee, an elementary school student headed to his grandmother’s house, was shot in the head and back Monday in a neighborhood alley on the city’s South Side.

McCarthy told reporters Thursday that the slaying was the result of two gangs fighting, potentially in a string of retaliatory events dating back months. He said the boy’s father isn’t cooperating with police.

McCarthy called it probably the "most abhorrent, cowardly unfathomable crime that I’ve witnessed in 35 years of policing."

"Everybody is sick; everybody is disgusted."

The child’s father, Pierre Stokes, has disagreed with authorities’ characterization of him and said he’s easy to find. He hasn’t talked about whether he’s a gang member but said police have spent more time pursuing him than finding out who killed his son.

"I answered every question they asked me," he told reporters Thursday not far from the spot his son was killed. "They’re not asking me questions that I know. I don’t know the questions that they asked me."

A memorial for the boy — stuffed animals, candles and balloons — lingers in the alley.

Police have executed several search warrants in the investigation, but refuse to release details. A "person of interest" turned himself into police Wednesday and was released between late Wednesday and early Thursday without charges.

Authorities have said they know the gangs and individuals involved but need help assessing who did what. They reiterated a plea for any information that will help lead to charges, acknowledging fears people may have of being targeted for speaking out.

"We’ll take those steps to keep it as quiet as we can," McCarthy said.

At least $35,000 is being offered for information leading to charges in connection with the boy’s death. Members of the Faith Community of St. Sabina, a well-known South Side Roman Catholic church, have raised money from around the country.

The Rev. Michael Pfleger, a priest at St. Sabina who is known for his anti-violence activism, said he would pay money out of his own pocket to help anyone with information move from Chicago.

"This was not a drive-by. This was not a spray of bullets. A baby was executed," Pfleger said. "We have gone to a new low that’s removed what used to be some codes, some barriers, some lines that used to be drawn in the community, some things in our city that were not acceptable."