An expert report produced by a retired Chicago police sergeant alleges Evanston police committed misconduct in the mistaken handcuffing of 13-year-old Diwani Greenwell, the son of Medill Prof. Ava Greenwell.

Evanston Police Department officer Mark Buell handcuffed Diwani Greenwell on the morning of Aug. 20 when the boy was riding a bike around his house. EPD officers said the teen matched the description of a burglar suspect, which described the suspect as a “black male wearing blue cargo shorts.” The officers released the teen about ten minutes after the handcuffing when the witness exonerated him.

The Greenwells filed a federal lawsuit against the city and Buell in September for alleged racial profiling. An EPD internal investigation cleared Buell in November.

Stephen Sherwin, a Vietnam War veteran who reportedly served the Chicago Police Department from 1967 to 2005, issued a report evaluating EPD performance during the handcuffing in mid January. Christopher Cooper, the Greenwell family’s attorney, hired the retired officer to produce the report, Sherwin said.

In his report, Sherwin alleged the Evanston police officers made a series of mistakes during their search for the burglar suspect.

The report contended Diwani Greenwell did not match the witness’ original description of the burglar suspect. The witness reported to 911  the burglar was a black male wearing khaki shorts, a brown T-shirt or a dark shirt, whereas Diwani Greenwell wore a grey shirt and dark blue shorts. Miscommunication between the 911 operator and field officers added to the confusion, the report said.

“Diwani Greenwell’s physical description did not match that of the wanted person other than being African American and wearing shorts,” Sherwin wrote in the report.

The report also alleged officers did not have “reasonable suspicion” justifying handcuffing the boy, who “remained calm, polite and cooperative” during the handcuffing without attempting to flee. The seven officers on the scene was “a rather large show of force” compared to the unarmed teen, Sherwin wrote.

“A major question is, did the Evanston police officers know at the time they interacted with Diwani Greenwell, when they stopped and handcuffed him, that he was not the offender?” he wrote. “The answer is, yes.”

The report also alleged EPD Sgt. Angela Hearts-Glass glossed over police mistakes when presenting the internal investigation results to the city’s human services committee Nov. 5.

Sherwin declined to comment on his report due to the impending litigation.

“I stand by my report,” he said.

Cooper said he introduced Sherwin to the family because he is experienced in street duty. Sherwin’s testimony would help the case succeed to trial by establishing material facts in dispute, he said.

“As a general rule, expert testimony certainly heightens concern of the parties,” Cooper said.

EPD spokesman Cmdr. Jay Parrott said the police had not seen the report. Parrott declined to comment due to the pending litigation, but expressed confidence about the case.

“We feel confident that the lawsuit will work out in the city’s favor,” he said.

Ina Yang contributed to reporting.