It is next to impossible to be an undercover CSI. This is because, as someone has already mentioned, the name says it all (crime scene investigation), which means the investigation/collection of evidence that may connect the suspect to the crime scene. Second, exclusion rule states states that any evidence collected in violation of the Constitution will be inadmissible in the court of law. Thus, evidence collected during an undercover operation will not easily find its way to the court. And finally, there are rules (of evidence) that need to be followed when collecting, transporting (chain of custody), and preserving evidence, otherwise they will be considered tainted, thus, inadmissible. These rules will be hardly followed and there will be difficult to determine the integrity of evidence collected during an undercover operation at trial. In Short, undercover CSIs may exist, but their work will be unproductive at trial.