Tioni Theus, 16, was found dead in January along an onramp of the 110 Freeway. On Tuesday, L.A. City Councilmembers Curren Price and Marqueece Harris-Dawson introduced a motion for a $50,000 reward for tips leading to the arrest and prosecution of Tioni’s killer. “It’s disheartening to know that the person or persons responsible for her killing are still on the …