Killer Apps

Updated at 5:00 p.m. ET on August 9, 2023

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One fall evening in 2020, Jarell Jackson and Shahjahan McCaskill were chatting in Jackson’s Hyundai Sonata, still on a postvacation high, when 24 bullets ripped through the car. The two men, both 26, had been close friends since preschool. They’d just returned to West Philadelphia after a few days hang gliding, zip-lining, and hiking in Puerto Rico. Jackson was parked outside his mom’s house when a black SUV pulled up and the people inside started shooting. Both he and McCaskill were pronounced dead at the hospital.

In the aftermath, McCaskill’s mother, Najila Zainab Ali McCaskill, couldn’t fathom why anyone would want to kill her son and his friend. Both had beaten the odds for young Black men in their neighborhood and graduated from college. Jackson had been a mental-health technician in an adolescent psych ward while her son had run a small cleaning business and tended bar. She wondered if they’d been targeted by a disgruntled former employee of the cleaning business. But then the police explained: Her son and his friend had been killed because of a clash on social media among some teenagers they’d never even met.

For months, a battle