blood samples
I guess the rules changed since 2020:
CBP is NOT collecting DNA from persons encountered under the following circumstances:
Aliens lawfully in, or being processed for lawful admission into the United States;
Aliens held at a Port of Entry during consideration of admissibility and not subject to further detention or proceedings;
Aliens held in connection with maritime interdiction;
or When the FBI system, NCIC, indicates CODIS already contains a DNA profile for the individual.