Who is Angel Baptista from Darkly Dreaming Dexter and what is their importance?

Angel Batista is employed as an investigator in the medical examiner's office. He and Dexter often work together, most recently on Tamiami Trail case. Angel makes crucial observations about the killer that lead Dexter to conclude the killer is growing bored with his ritual and looking for new ways to kill his victims. This information helps Deborah make several breakthroughs in the case.