Nine-year-old Tyshawn Lee carried his basketball with him wherever he went.
It was with him after he bid his grandmother goodbye one unseasonably warm day in November 2015, telling her he was going to “shoot some hoops.” He set it down next to the jungle gym at Dawes Park as he played.
And a short time later when he was found dead -- shot repeatedly at point-blank range in a nearby alley -- his basketball was only a few feet away.
Samples from the basketball were sent to Illinois State Police forensics experts, but traditional methods of analysis came up short.
So the state police lab, which handles much of the forensic analysis of evidence in Chicago-area criminal investigations, turned to a method it had never before used: “probabilistic genotyping” software called STRmix to interpret DNA samples that are too complex for older systems to handle.
On Tuesday, at the trial of two reputed gang members charged in Tyshawn’s killing, Dr. John Buckleton, STRmix’s co-creator, testified that the analysis found a “very strong possibility” that the accused gunman’s DNA contributed to the mix found on three out of four samples from the basketball and a “strong possibility” on the fourth sample.
The testimony at the trial of Corey Morgan and Dwright Doty marked the first time that such evidence has been used in a state court in Illinois, Buckleton acknowledged from the stand.
Cook County prosecutors allege Doty fired the fatal shots into Tyshawn as part of an escalating feud between two gang factions, deliberately targeting the skinny fourth-grader just weeks after a rival gang connected to his father fatally shot Morgan’s brother and wounded his mother.
Buckleton’s analysis also found statistical support for Doty’s profile being included in the DNA mixture on some of the swabs from the alleged getaway car, he testified.
Prosecutors hope the controversial DNA evidence will bolster testimony from an eyewitness that a man -- identified by prosecutors as Doty -- bounced Tyshawn’s basketball and talked with him shortly before luring him to the alley and shooting him.
Before the trial, defense attorneys fought hard to keep prosecutors from introducing the DNA analysis to the jury, arguing that the methods were not necessarily reliable. The defense likely feared that jurors would hear the word “DNA” and simply assume the evidence was unimpeachable.
After a two-day hearing last June, Judge Thaddeus Wilson ruled that jurors could hear about Buckleton’s conclusions -- because Illinois law required him to determine only if the methodology was “generally accepted,” not whether an expert’s testimony would be reliable or relevant.
The decision made him “uneasy,” though, the judge wrote in his order in July, especially given that other kinds of forensic evidence once widely considered reliable -- such as footprint and microscopic hair analyses -- have since come under fire.
“While a judge can be confident he has applied (case law) correctly, he cannot help but wonder whether he has pushed life and liberty into the cesspool of junk science,” he wrote.
Wilson seemed particularly concerned that the organization behind STRmix at first tried to “hide behind trade secret protections,” he wrote.
They were “acting more like a company hawking male enhancement drugs with secret proprietary blends,” he said.
Wilson later withdrew his initial written order and replaced it with a similar one but less strongly worded and without reference to the pills or “cesspool.”
Buckleton, a forensics expert from New Zealand who helped develop the STRmix system, testified that the technology has been used by 46 U.S. laboratories, including ones affiliated with the the FBI and U.S. Army.
“Probabilistic genotyping” was considered a breakthrough, analyzing samples that involve multiple DNA profiles that traditional methods couldn’t pin down, he said.
On cross-examination by one of Doty’s attorneys, Buckleton said the STRmix results should be viewed in light of all the other available evidence.
Assistant Public Defender Michael Buresh also asked if Buckleton knew of the pressure faced by Chicago police and prosecutors to solve the killing.
“I believe (the case) was considered important,” Buckleton told separate juries deciding the defendants’ fate. “They were prepared to invest resources in this.”