(a) Whenever the Mayor has probable cause to believe that any person within the District of Columbia, other than a person referred to in subsection (b) of this section, is a drug user, he forthwith shall order any law enforcement officer of the District of Columbia to bring that person before him, to conduct a preliminary examination, and if he finds sufficient evidence of addiction, as hereinbefore defined, he shall cause that person to be placed in an institution to be designated by him for an examination by physicians pursuant to § 24-705.
(b) The Mayor shall not order any person brought before him if the said person is charged with a criminal offense, whether by indictment, information, or otherwise, or if the said person is under sentence for a criminal offense, whether he is serving the sentence, or is on probation or parole, or has been released on bond pending appeal.