Image copyright AP Image caption Dwright Boone-Doty, 22, is the second person charged over the death of Lee

A man has been charged with murder over the fatal shooting of a nine-year-old boy in Chicago, apparently because of his father's gang ties.

Dwright Boone-Doty, 22, was arrested on Monday night in connection with the death of Tyshawn Lee in November.

He is the second suspect to be charged over the killing, which caused an outcry in Chicago.

Corey Morgan, 27 - said to be one of two men who lured Lee from a playground - was arrested in November.

On Tuesday a prosecutor said the murder was symptomatic of an "unprecedented crisis" of gang violence in the city.

More than 450 people were killed in Chicago in 2015. The city police department faced intense criticism and a murder charge for one of its officers over the shooting of a 17-year-old black teenager Laquan McDonald.

Police says Boone-Doty was being held on unrelated gun charges when investigators linked him to the child's death.

Image copyright AP

Then-Police Superintendent Garry McCarthy described the shooting as the "most abhorrent, cowardly, unfathomable crime" he had ever seen.

Police officials and prosecutors echoed that language on Tuesday.

Media playback is unsupported on your device Media caption Police described the crime as "unfathomable"

"In my nearly 30 years of policing, I have never witnessed such a hateful act of treachery," said Police Superintendent John Escalante.

State's Attorney Anita Alverez said Boone-Doty had been looking for family members to kill - including Tyshawn's grandmother - as part of escalating gang retribution.

He allegedly lured Lee to the alley where he was killed by promising to buy him something.

Boone-Doty's original plan, Alverez said, was to torture the young boy by cutting off his fingers.