The United States government has collected DNA samples from upwards of 133,000 migrant children and teenagers—including at least one 4-year-old—and uploaded their genetic data into a national criminal database used by local, state, and federal law enforcement, according to documents reviewed by WIRED. The DNA samples are registered in the Combined DNA Index System, or CODIS, a database administered by the FBI, which processes the DNA and stores the resulting genetic profiles. A network of criminal forensic databases, CODIS is used by local, state, and federal enforcement agencies to match DNA collected from crime scenes or convictions to identify suspects. According to CBP records, the individual was just 4 years old. Department of Homeland Security policy states that individuals under 14 are generally exempt from DNA collection, but field officers have the discretion to collect DNA in some circumstances.