(a) An officer may arrest a person without a warrant, on any day and at any time in any of the following instances:
(8) When an offense involves domestic violence as defined in Section 13A-6-139.1 or elder abuse as defined in Section 38-9F-3 , and the arrest is based on probable cause, regardless of whether the offense is a felony or misdemeanor.
(b) When a law enforcement officer investigates an allegation of domestic violence or elder abuse, whether or not an arrest is made, the officer shall make a written report of the alleged incident, including a statement of the complaint, and the disposition of the case.
[Emphasis added.]