What do authorities use as guidelines when they declare somebody missing and start an investigation?
When police receive a report of a missing person, they gather all the relevant data needed and determine the circumstance of the case. They use a system called LEIN, which is the Law Enforcement Information Network.
The network connects police agencies across the country. If a missing person is found or has contact with law enforcement, they can run their name and it will show that they are missing.
"We do not have to wait, as a law enforcement agency, 24 hours before you can report somebody missing or before we actively look for somebody," said Detective Michael Kohler of the Marquette Police Department. "If there's a concern we believe the person is involuntarily missing, then we can start actively looking for that person or putting that person into our database, especially under the age of 21."
For a juvenile, the criteria are less strict than if the person is over 21 years of age.
"This is something we all need to know and hope we'll never have to do," said Facebook user Kathy Sylvester.
Law enforcement officials have several categories for missing persons, including runaway, disabled, or endangered.