The video in this story is from a previous report
Police said the stabbing occurred at about 1 a.m. on a train at the Cermak station.
A 31-year-old man suffered an injury to his arm and was transported to Northwestern Memorial Hospital in fair condition.
Policer said David Davis, 31, of Freeport, Illinois has been charged with aggravated battery/use of a deadly weapon, aggravated battery of a transit employee, attempted armed robbery and possession of a controlled substance