Each homicide team consists of a detective sergeant, four detectives, and a laboratory evidence technician. Because the first 24 to 48 hours following a homicide are critical to a successful investigation, the team concept ensures that there are adequate personnel at the scene. The first officer on the scene is responsible for preserving the crime scene intact, removing all unauthorized persons from the area, erecting a physical barrier, conducting preliminary interviews with witnesses, arresting the suspect if possible, and maintaining accurate and complete notes. Then, a patrol officer or uniformed supervisor briefs the homicide team as a group, and two detectives interview the suspect if there is one in custody. At the crime scene, the detective designated as crime scene investigator records and documents the scene through photographs, diagrams, and a narrative. Evidence is collected including trace samples, fingerprints, weapons, documents, and other forensic samples. In addition, the team conducts a methodical search of the surrounding area. A thorough examination of the body is made at the morgue, and the subsequent autopsy is witnessed by the investigator. When a suspect has been identified and evidence gathered against him, the police make a presentation to the District Attorney and seek the filing of a complaint.