Cal. Gov. Code § 31558.8
Notwithstanding any of the provisions of Section 31558 to the contrary, a person over 35 years of age who is employed by a county of the third class, as established by Sections 28020 and 28024, as amended in 1971, as a detective or investigator in the office of the district attorney, which would make the person eligible to become a safety member if he or she had not been over the age of 35 years at the time of his or her employment, may, if he or she so elects, become a safety member as of the first day of the calendar month following his or her entrance into county service regardless of age.
A member may receive credit for that service, as a safety member, when he or she has contributed, with interest to the date paid, the difference between contributions made and those which would have been made by the member if he or she had been a safety member. The additional contributions shall be made prior to retirement.
This section shall not be operative in any county until such time as the board of supervisors shall, by resolution adopted by majority vote, make this section applicable in the county.
Ca. Gov. Code § 31558.8