In addition to existing powers of promotion in the bureau of police, cities of the second class are hereby authorized to create such additional classes of detectives as they shall determine to be designated as Detective Class I, Detective Class II and Detective Class III. Such classes of detectives shall carry salaries which shall not be less than the maximum of salaries of patrolmen and not greater than the minimum salaries of detectives presently existing in cities of the second class, and shall consist of members of the police bureau who have been assigned to such additional classes of detectives because of a particular aptitude for investigation, outstanding meritorious service, or unusual and exceptional bravery.

Assignments to the several additional classes of detectives shall be made in the following manner. Whenever a member of the police bureau is recommended by his superior officer for assignment to one of the additional classes of detectives authorized in this section a police merit board shall be convened.

The board shall be constituted in each instance in the same manner as police trial boards authorized by law. The police merit board shall hear such evidence as may be pertinent to the case and shall thereafter make its recommendation. Such recommendation shall then be forwarded to the superintendent of police who shall endorse thereon his approval or disapproval of the board's finding. Thereafter the said report with the endorsement of the superintendent of police shall be submitted to the director of the department of public safety who shall take such action thereon as in his discretion he deems proper. In case of such assignments to an additional detective classification the member of the bureau of police so assigned shall retain his civil service status under the civil service laws then in effect. Whenever for any reason within the discretion of the director of the department of public safety it is deemed necessary or desirable to reassign any such member to his former position the said director of the department of public safety shall have the right to make such reassignment. Civil service commissions of cities of the second class may, in their discretion, make such rules and regulations for grades, merits, or credits, concerning the positions authorized by this section and relating to promotional examinations for such positions in the bureau of police as they may see fit. Rules and regulations relating to promotional examinations shall not require as a condition of taking any such examination that the applicant have any experience or service other than the completion of four years of service in the bureau of police.