Which concept is referred to by the abbreviation CODIS?

The correct choice refers to the Combined DNA Indexing System, which is a crucial tool used in the field of criminal investigation and forensic science. CODIS operates as a national database that allows law enforcement agencies to compare DNA profiles from crime scenes with profiles from known offenders, as well as profiles collected from missing persons or unidentified remains.

This system significantly enhances the ability of investigators to solve crimes by providing connections between different incidents that may not have been previously linked. Its effectiveness lies in the ability to compile and index DNA samples from various sources, which can be matched against one another to identify suspects or victims, thereby streamlining the investigative process.

The other options do not accurately describe CODIS, as they suggest various alternate meanings that do not exist in practice or do not emphasize the system's role in combining DNA profiles for criminal justice purposes. For example, terms like "Controlled" or "Civilian" do not capture the essence of a combined indexing system that serves law enforcement and forensic science.