FROSTPROOF, Fla. \- Polk County Sheriff’s Office is investigating a homicide that happened in Frostproof Saturday afternoon. According to Polk County Sheriff Grady Judd, just after 2:00 p.m., 21-year-old Emmanuel Espinoza, who is a pre-med student at the University of Florida, drove to his mother’s house in Polk County and stabbed her to death. He called 911, confessed, and is in custody. Read: 76-Year-Old Lakeland Pilot Killed In Plane Crash In South Lakeland Elvia Espinoza, 46, was a second-grade teacher at Ben Hill Griffin Elementary School in Frostproof. “Her family, friends, students, and…