(a) Service of a criminal witness subpoena upon a law enforcement officer or upon any federal, state, or municipal employee called to testify in an official capacity in a criminal case may be made as provided in subsection (1) or by delivery to a designated supervisory or administrative employee at the witness's place of employment if the agency head or highest ranking official at the witness's place of employment has designated such employee to accept such service. However, no such designated employee is required to accept service:
1. For a witness who is no longer employed by the agency at that place of employment;
2. If the witness is not scheduled to work prior to the date the witness is required to appear; or
3. If the appearance date is less than 5 days from the date of service.
The agency head or highest ranking official at the witness's place of employment may determine the days of the week and the hours that service may be made at the witness's place of employment.