PHILADELPHIA -- Violence between biotech protesters and police in Center City Philadelphia has turned tragic. A Philadelphia police officer has died after a scuffle in Center City on Tuesday. The officer, Paris Williams, 52, may have died from a heart attack but homicide is also investigating the case. He is a 19-year veteran. Williams collapsed near the end of a brawl between protesters and police that lasted for several minutes near 12th and Arch Streets. Some protesters were seen being taken away in handcuffs by police after the incident. The fallen officer was taken away in an ambulance. Police department...