Capt. Patrick Foy says Friday that investigators determined the singer didn't have a permit for the capuchin monkey, named Fiji.
The singer posted an Instagram video last month showing his 3-year-old daughter, Royalty, cuddling with the monkey. Foy says that prompted a half-dozen calls to the wildlife department from concerned people.
Foy says Brown agreed to cooperate. Agents served a search warrant Jan. 2 at his home.
Foy says Brown wasn't there but had employees hand over the monkey in a cage.
Fiji is now at an undisclosed facility.
Brown could face a misdemeanor charge carrying a potential six-month jail sentence.