 Several aspects of popular crime shows have been criticized as being unrealistic . For instance , the show 's characters not only investigate ( " process " ) crime scenes , but they also conduct raids , engage in suspect pursuit and arrest , interrogate suspects , and solve cases , which falls under the responsibility of uniformed officers and detectives , not CSI personnel . Additionally , if CSIs process a crime scene it is inappropriate for them to also be involved in the examination and testing of any evidence collected from that scene as it would compromise the impartiality of scientific evidence . In real investigations , DNA and fingerprint data is often unobtainable and , when they are available , can take several weeks or months to process , whereas television crime labs usually get results within hours . In the first season of CSI , technicians made a plaster mold of the interior of a wound to determine the type of knife used to make the wound , which is not possible with current technology . Characters on television often use the word " match " to describe a definitive relationship between two pieces of evidence , whereas real forensic technicians tend to use terms that are less definite , which acknowledges that absolute certainty is often not possible . 
