Sgt. Harold Preston was a 41 year veteran of the Houston Police Department. He was the caretaker for his elderly parents. 65 years old, he was just a few weeks away from retirement. He was shot and killed Tuesday morning in the line of duty. Preston was shot by Elmer Manzano, an illegal alien and convicted felon with multiple priors. In October 1994, Manzano was arrested for the unlawful carrying of a firearm in Dallas County. That case was dismissed after a year of deferred adjudication, according to Dallas County court records.In August 2000, Manzano was arrested for assault in...