The Tampa Police Department (TPD) activated a Purple Alert on Tuesday morning for a missing 20-year-old man with autism.Police said Zachariah Robert Davis was last seen leaving his residence in the 8300 block of North 13th Stree t at around 10 p.m. on April 6.Davis was last seen wearing a white jacket, khaki pants and black shoes, per the alert.Police also said he functions at the cognitive level of a 12-year-old.Officials urge anyone with information on Davis's whereabouts to call TPD at 813-231-6130. ...read more read less