A homeless man murdered a 14-year-old riding his bike without provocation or motive, Miami police said Thursday. Police discovered Ryan Rogers’ body on the side of an interstate highway. He died of stab wounds to the head on Nov. 15. Palm Beach Gardens Chief Clinton Shannon said, “This appears to be a completely random act. We do not have a motive. I would best describe it as an innocent child victim having a chance encounter with a very violent criminal.” Thirty-nine-year-old Semmie Lee Williams faces first-degree murder charges following his arrest in Miami Wednesday. He has a long history of violent crime that includes throwing a man into a ravine after choking him.