A human head washed ashore at a popular South Florida beach on Nov. 12, authorities say.Miami-Dade police are investigating the incident after a beach worker in Key Biscayne, Florida discovered the decapitated head early Tuesday morning behind the Key Colony II Ocean Sound condos, according to multiple reports.The police have not been able to identify the specifics regarding the head and are unaware of the age or sex, CBS Miami reported.MEXICAN MAYOR'S SEVERED HEAD PLACED ATOP PICKUP TRUCK 6 DAYS AFTER TAKING OFFICEThe cause of the decapitation is still under investigation, Miami-Dade Police Detective Andre Martin told NBC News."We have