Article 18 of Code of Criminal Procedure and Trials

A- If it is not possible to deliver a copy of the notice to the person summoned to appear or to one of his relatives residing with him at his place of residence, because none of them is present or because they refuse to receive it, the copy shall be delivered on the same day to the officer in charge of the police station, or the person acting in his stead, within whose district the domicile of the person summoned to appear is located. The person effecting service shall, within 24 hours of delivering the copy to the police station, send a registered letter by post to the person summoned to appear at his domicile, notifying him that the copy has been delivered to the police station. He shall record at the time—in the original notice and its copy—all the steps he has taken to effect service. B- If the domicile of the person summoned to appear is unknown, a copy of the notice shall be delivered to the Public Prosecution or the Public Prosecutor's Office, as the case may be. C- Violation of the provisions of this Article shall entail nullity.