Tearful teen suspect charged with murder as cops recover knife, sweatshirt after random fatal stabbing of beloved NYC activist

The 18-year-old man suspected in the random stabbing death of a beloved Brooklyn social-justice activist was arrested on Thursday – as cops raiding his apartment found a knife and a sweatshirt matching the one the attacker wore, police and sources said.

Brian Dowling was pictured with tears running down his face – and cuffs around his wrists and ankles – as officers escorted him from the NYPD’s 81st Precinct in Bedford–Stuyvesant after charging him with murder and criminal possession of a weapon.

The accused killer was wearing the same white T-shirt and striped shorts as when cops busted him at his home on…