Rex is trained for therapy work, explosives detection and tracking.
That combination means his work can extend across very different situations.
As a therapy dog, he can interact with children and provide a calming presence.
As an explosives-detection K-9, he can help law enforcement identify specific odors associated with dangerous materials.
And as a tracking dog, he can help locate missing people.
Each role requires a different type of training and behavior.
A therapy dog needs to be calm and approachable.
A detection dog needs to be focused and able to identify target odors.
A tracking dog needs to maintain concentration while following a scent trail.
Rex has been trained to perform all three.
His first successful missing-child search showed how those skills can complement one another.
The tracking ability helped locate the child.
The therapy training helped comfort her afterward.
Rex's Journey Began as a School Therapy Dog
Rex's connection with children did not begin with this missing-person case.
The Arapahoe County Sheriff's Office's annual report identifies him as a therapy dog who worked with Littleton Public Schools and Deputy Gray.
That role gave Rex regular opportunities to interact with students.
For a school-based therapy K-9, being comfortable around children is essential.
The dog must be able to remain calm in busy environments and respond appropriately when children are anxious, upset or experiencing difficult circumstances.
Rex's experience in that environment later became relevant during the missing-child search.
The girl had just been through a frightening experience.
She needed to know that she was safe.
And Rex was able to remain beside her.
The same dog that had spent years helping children in schools had just helped deputies locate a child in an emergency.
Training Only Matters When the Moment Arrives
For months, Rex and his fellow K-9s trained for the possibility of being called into a real search.
But training exercises can only simulate an emergency.
There is a difference between following a practice trail and searching for a real child whose family is waiting anxiously for her return.
That is why the first successful mission mattered so much.
Deputy Gray told Denver7 that completing training is not really the end of the process; it is when the practical work begins.
Rex's first real mission provided that test.
There was a missing child.
There was a real family waiting.
There were deputies searching.
And there was a scent trail that Rex needed to follow.
He responded.
Why Every Minute Matters When a Child Goes Missing
The emotional power of the story also comes from the time involved.
The girl had been missing for approximately two hours before Rex and Gray joined the search.
Two hours may not sound long in ordinary circumstances.
But when a young child is missing, two hours can feel endless to a family.
Parents may not know whether their child is nearby or has traveled farther away.
They may not know which direction to search.
They may not know whether the child is frightened, injured or simply hiding.
That uncertainty is one of the most difficult parts of a missing-person situation.
A tracking dog can potentially reduce that uncertainty by providing investigators with information about where a person has traveled.
In this case, Rex's ability to narrow the search area helped deputies find the girl after only about 12 minutes of tracking.
The contrast is remarkable:
Nearly two hours of uncertainty.
Twelve minutes of tracking.
One safe child.
The Human-Dog Partnership Behind the Rescue
Stories about K-9s sometimes make it sound as if the dog works alone.