We find missing persons. Police usually deal with cases of missing vulnerable persons, such as children the elderly and those with disabilities. However, a capable adult is perfectly entitled to disappear and leave their family behind – and many do. Private investigators are often retained by parents and other family members wanting to trace a missing son, daughter, or parents. Approximately 180,000 missing persons cases are reported every year in the UK. Some of the more common reasons for adults to go missing include relationship difficulties and mental health problems.