The International Association for Identification (IAI) is one of the few professional organizations that certifies crime scene investigators. The IAI's Crime Scene Certification Program offers comprehensive testing in three levels of certification: Level 1--Crime Scene Technician; Level 2--Crime Scene Analyst; and Level 3--Senior Crime Scene Analyst. All levels require applicants to take a written test that is administered in a controlled setting. As more attorneys question crime scene investigators about their expertise, an increasing number of police agencies will expect that crime scene investigators attain some form of certification. Crime scene personnel who are not certified tend to be only collectors of evidence that is then delivered to the forensic lab without any interpretation. The ideal situation is for certified crime scene investigators and forensic scientists to work together and share ideas at the crime scene. In presenting a strong case in court, the prosecution will often call crime scene investigators to testify about evidence found at the crime scene. Certification will add credibility to a crime scene investigator's testimony. Further, it provides the necessary background for conducting more accurate and thorough investigations.