The police are part of the executive branch, constitutionally speaking.
To pick my final nit of the evening, this is usually true, but not always. Many court systems and legislatures maintain their own police forces independent of the executive power. I suppose the rule technically holds for university and private-sector police forces, which presumably face regulation from within the executive branch.
-- "Hige sceal þe heardra, heorte þe cenre, mod sceal þe mare, þe ure mægen lytlað."