They have one, and at least hypothetically have the power to order Paul D. Irving to raise a posse and effect an arrest. It’s not been done since the 1930’s, but it could be. Given Congress’s plenary power over the District of Columbia, the posse would likely consist of the DC Metropolitan Police.
Long paper on the subject from the Congressional Research Service: https://fas.org/sgp/crs/misc/RL34097.pdf
