A 31-year man has been arrested in connection with an armed robbery targeting two teenagers in Brooklyn.
Investigators say Christopher Donohue approached the victims on a southbound F train in July.
Donohue is accused of displaying a knife and forcibly removing one of their backpacks.
The backpack contained a wallet with $440 dollars.
Police say Donohue has been charged with two counts of robbery and criminal possession of a weapon.