File a police complaint immediately
There is no need to wait 24 hours. Go to the nearest police station with a recent photograph and details of when and where the person was last seen.
Gather information
Note what they were wearing, their phone number, any vehicle, regular places and recent changes in mood or behaviour.
Contact people they know
Friends, colleagues and relatives may have information. Keep a written record of every conversation.
Keep their phone and accounts untouched
Do not try to access their accounts. Share information with the police, who can act lawfully.
How a private investigator helps
Alongside the police, an investigator can follow lawful leads, make enquiries at places frequented and keep the family informed.