Keananna Streeter, 18, was arrested Friday for stabbing her ex-boyfriend’s new girlfriend tabbed her ex-boyfriend’s new girlfriend Ragan McDougle because he wasn’t helping her raise their baby.She is charged with first-degree murder, according to the Chicago Sun-Times. She was ordered held Sunday on $500,000 bail in connection with the Sept. 1 stabbing that left a 32-year-old woman dead.