By the time Deputy John Gray and K-9 Rex joined the search, a 7-year-old girl had been missing for nearly two hours.
Deputies had already begun looking around the Arapahoe County, Colorado, neighborhood where she disappeared on April 2, 2026.
Other resources were involved too.
Then Rex was given something that changed the search.
A pair of the girl’s shoes.
The 5-year-old black Labrador lowered his nose and took in the scent. After that, he and Gray started moving.
Twelve minutes later, deputies found the child in a nearby backyard.
She was unharmed.
And for Rex, the successful track carried another distinction.
It was the first successful missing-child find for him after months of specialized tracking training.
The Search Had Already Been Underway for Nearly Two Hours
The girl had been visiting a park with her family when she ran off.
According to the Arapahoe County Sheriff’s Office account quoted in reports about the search, deputies responded to the 6400 block of South Telluride Street after the child ran away because she did not want to leave the park.
Deputies, K-9 units, and drones began searching the area.
Nearly two hours passed.
For a family waiting for a missing child to be found, that is a long time.
Then Gray arrived with Rex.
Rex Had a Way to Search That People Did Not
A human searcher can look down streets.
Check playground equipment.
Talk to neighbors.
Search yards.
Review likely routes.
Rex brought another tool.
Scent.
Gray was given the girl’s shoes so Rex could identify an odor associated with the person they were trying to find.
Once the Labrador had the scent, the pair began tracking.
This was not a matter of simply letting a dog loose and hoping he happened to choose the right direction.
Rex had spent months learning how to work a trail with his handler.
His Nose Was Only Part of the Job
Gray later explained that Rex’s value went beyond showing deputies where the girl had gone.
The dog also helped indicate where she had not traveled.
That allowed searchers to narrow the area instead of treating every possible direction as equally likely.
“It was really essential that he not only took us to the area where she went, but he communicated to us where she didn’t go,” Gray told Denver7.
As a result, deputies could focus their attention more efficiently.
In a missing-person search, that matters.
Every unnecessary area ruled out leaves more people and time available for the places that remain.
Rex Picked Up the Trail
The shoes gave him the scent reference.
Then his training took over.
According to Gray, the sheriff’s tracking dogs had already been scent-trained before beginning their more specialized missing-person work. During that training, they learned to follow signs such as human odor and disturbances along the ground.
Those cues are largely invisible to the people walking behind the dog.
Rex, however, had been trained to work through them.
Gray’s job was to read him.
That relationship between dog and handler was as important as the Labrador’s nose.
Twelve Minutes Later, The Search Reached a Backyard
Rex led deputies toward a nearby yard.
There, the missing girl was found.
Only about 12 minutes had passed since Rex began tracking from the scent on her shoes.
The sheriff’s office later said that the frightened child tried to run again once deputies reached her.
Deputy Halliburton caught up with her safely.
Soon afterward, she was reunited with her family.
After nearly two hours of uncertainty, the search was over.
Rex Had Never Made a Find Like This Before
That is one of the details that made the search stand out.
Rex was not an inexperienced dog.
By then, he had spent years working with Gray and had received several forms of specialized training.
However, this was his first successful live missing-child track after completing the sheriff’s office’s new tracking program.
Denver7 described the case as the first successful find for the Arapahoe County Sheriff’s Office tracking team.
Training had prepared Rex for the possibility.
April 2 was the day that preparation became a real search involving a real child.
Gray Had Spent Months Preparing for That Moment
Rex was one of three dogs involved in the department’s specialized tracking effort.
The team included Rex, Riley, and Bear.
According to Denver7, the dogs trained for approximately 16 months. They already had scent-related skills, but the new program taught them to work missing-person tracks by following ground disturbances and human odor.
Training a working dog does not end when a certification is earned.
Gray put it simply:
“Once you are done training, that’s kind of when the training actually starts.”
Real environments do not behave like controlled exercises.
Wind changes.
People cross a trail.
Cars pass.
Surfaces change.
A handler and dog have to keep practicing if the skill is going to remain useful.
Rex’s Career Had Started With a Very Different Assignment
Years before anyone handed Rex a missing child’s shoes, he had another job.
Comforting students.
Littleton Public Schools announced Rex’s arrival in May 2021, when he was a 10-week-old black Labrador puppy assigned to Gray, a school resource officer working with elementary schools.
At the time, Rex’s mission was to become a therapy dog for students.
The district said he would work with children experiencing stress and help support students in crisis, including those struggling with anxiety or other emotional challenges.
He still had a great deal of growing and training ahead of him.
Nobody looking at that small Labrador puppy could have known exactly where his career would eventually lead.
Therapy Work Required a Different Kind of Skill
A school therapy dog is asked to do almost the opposite of what people imagine when they hear the words “police K-9.”
There is no dramatic pursuit.
No suspect apprehension.
Instead, the dog has to remain manageable around children.
He needs to work calmly in busy environments.
He may sit beside a student who is overwhelmed.
Walk through hallways.
Attend community events.
Or simply provide a familiar presence during a difficult day.
Rex became part of that work alongside Gray.
In 2021, the sheriff’s office listed his introduction as one of the agency’s notable developments that year.
Then Rex Added Explosives Detection
His career continued expanding.
After beginning as a therapy dog, Rex was trained in explosives detection.
Riley and Bear also received that training.
Later, the three Labradors entered the intensive tracking program that would eventually put Rex on the trail of the missing girl.
By 2026, Rex was certified in three distinct areas: therapy work, explosives detection, and tracking.
The RexRun for PAWSitivity organization, which supports area K-9 teams, lists Gray and Rex together and describes the black Labrador as trained and certified in all three disciplines.
Gray has called him a “triple threat.”
The description makes sense.
Each job asks something different of the same dog.
A Tracking Dog Has to Communicate With His Handler
Rex could not tell Gray, in words, where the child had gone.
Instead, Gray had to recognize the signals the dog gave while working.
A change in direction can matter.
So can hesitation.
The way a dog moves through an intersection or works an area can help an experienced handler decide whether the trail continues there.
That was why Gray emphasized that Rex helped show deputies not only the girl’s route but also directions they could eliminate.
A tracking K-9 therefore does not replace the search team.
The dog adds information to it.
Humans still coordinate the response, secure areas, deploy other resources, and act on what the K-9 team discovers.
The Search Was a Team Effort
Rex became the most recognizable part of the story because finding a child in 12 minutes is an extraordinary first successful track.
Still, he was one part of a larger response.
Deputies were already searching.
Drones were deployed.
Gray handled Rex.
Other deputies moved with the search.
Then Halliburton safely caught up with the child when she tried to run again.
That distinction is important in working-dog stories.
A K-9’s skill can be remarkable without turning the animal into a supernatural hero operating independently.
Rex did what he had been trained to do.
Gray interpreted his work.
Other deputies completed the rescue.
Together, they brought a child back to her family.
For Gray, The Successful Find Was Difficult to Describe
Months of training can feel theoretical until the skill is suddenly needed.
Gray had rehearsed these scenarios with Rex.
Then the real call came.
A child had been missing for nearly two hours.
The dog was given her shoes.
Twelve minutes later, the search team had reached her.
Gray later told Denver7 that seeing the training produce that result was hard to put into words.
“Being able to deploy him and see it pay off and get a girl safely home,” he said, “there’s not even really words you can use to describe it.”
The Job Changed As Soon As The Girl Was Found
Until that moment, Rex had one task.
Track.
Once deputies reached the child, however, there was no longer anyone to find.
That is where another part of his training became useful.
Rex returned to the role that had started his career.
Therapy dog.
According to Gray, Rex shifted from tracking work to helping comfort the girl after the frightening experience.
The same Labrador who had used her shoes to locate her could now simply be a calm dog beside a child.
Those Two Roles Look Very Different
During a track, Rex needs focus.
His nose is working.
Gray is watching him.
The team is moving with a purpose.
Once the missing person is found, the priorities change.
The girl no longer needed to be tracked.
She needed to be brought safely back.
She had been away from her family for nearly two hours and was frightened enough that she attempted to run when deputies first reached her.
In that moment, a black Labrador trained to be comfortable around children could become useful in an entirely different way.
No scent trail was necessary.
Just presence.
Therapy Had Always Been Part of Rex’s Identity
That is what makes his career unusual.
Many people picture a working K-9 primarily through enforcement roles.
Rex entered law enforcement differently.
From the start, he was intended to spend substantial time around children.
Littleton Public Schools described his original mission as bringing happiness and reducing stress among elementary students, including helping children in crisis.
Later training did not erase that role.
It added to it.
By the time of the April search, Rex could move between jobs depending on what Gray needed him to do.
His Handler Saw Value in That Combination
Gray explained after the rescue that dogs can affect how people respond during stressful experiences.
He specifically emphasized Rex’s ability to provide comfort to a child after a traumatic situation.
That did not mean the dog somehow erased what had happened.
The girl had still been missing.
Her family had still spent nearly two hours waiting for her to be found.
Deputies still had to safely reunite them.
But comfort does not have to solve a problem to matter.
Sometimes it simply makes the moments after the problem a little easier.
Rex Had Spent Most of His Life Around Students
The dog who made the track was already deeply familiar with schools and children.
Gray and Rex serve as school resource officers associated with Littleton Public Schools. RexRun describes the pair as working with the district’s elementary-school community.
That meant Rex’s first years of public service involved the same general age group as the girl deputies were trying to find.
On April 2, however, he was not meeting a student in a classroom.
He was following a child’s scent through a neighborhood.
The skills were different.
The purpose was ultimately similar.
Help bring a child to safety.
The New Tracking Team Had Been Created For Cases Like This
The sheriff’s office had a practical reason for investing in the program.
Missing-person calls are not rare.
At the time Denver7 reported on Rex’s successful track, the Arapahoe County Sheriff’s Office said it had already handled 58 missing-person cases during 2026.
Not every case requires a tracking dog.
Still, time can become critical when a young child, vulnerable adult, or lost person cannot be located quickly.
A trained K-9 gives search teams another option.
As Gray explained, every second can matter.
Sixteen Months Of Training Came Down To Twelve Minutes
That contrast is striking.
Rex, Riley, and Bear spent roughly 16 months preparing for specialized tracking work.
Rex’s first successful live find took 12 minutes.
That does not mean the job was easy.
It means the preparation allowed the team to work efficiently when the right call came.
Months of training are supposed to disappear into performance.
The handler gives the dog a scent.
The dog begins working.
The team follows.
On April 2, the trail ended where everyone hoped it would.
With the child alive and safe.
There Was Nothing Magical About The Shoes
They mattered because they carried the girl’s scent.
For Rex, they provided a starting point.
The rest came from training.
Dogs have remarkable olfactory abilities, but a strong nose alone does not create a working tracking K-9.
The dog has to learn what odor matters.
He must remain focused while other smells compete for attention.
The handler must understand when the dog is working confidently and when the trail becomes uncertain.
Rex and Gray had practiced that partnership long before anyone knew which real person they might someday need to find.
The Girl Never Had To Know How Complicated The Search Had Been
By the end of the incident, she was back with her family.
That was the result that mattered.
Behind it were deputies, search planning, drones, specialized training, a handler reading his dog’s signals, and one black Labrador following information the humans around him could not detect directly.
Then, once the work was done, Rex could stop being a tracker.
He could return to being the kind of dog children had known in Littleton schools for years.
Rex’s First Job May Have Prepared Him For The Last Part Of The Rescue
Tracking training helped find the girl.
His earlier therapy work gave him another role after the search ended.
That combination is what Gray found especially valuable.
A dog trained only to locate someone could still have done crucial work.
Rex could do that and then remain useful after the person was found.
The transition says something important about specialized working dogs.
Their value is not always defined by one skill.
Sometimes it comes from how several skills fit together.
The Sheriff’s Office Has Continued Building Around Dogs Like Rex
Rex is not the only therapy-oriented K-9 in the agency.
The sheriff’s office later added other school dogs, including Riley and Zeke. Its 2022 annual report noted the expansion of the therapy-dog program after Rex became its first school-resource therapy K-9.
By 2026, RexRun listed multiple sheriff’s office dogs working in therapy, detection, tracking, and other specialized roles.
Rex remained one of the most versatile.
His path had moved from elementary-school therapy dog to detection dog to trained tracker.
Then one April afternoon tied all three chapters together.
The Video Showed A Working Dog Doing Exactly What Training Was Supposed To Produce
Body-camera footage from the search showed Rex being given the girl’s shoes before beginning the track.
Later, the search reached the child.
Afterward, Rex received a reward for completing the work.
For viewers, the sequence took only minutes.
For Gray, it represented years.
Rex had arrived as a puppy in 2021.
He learned commands.
Worked with children.
Added detection skills.
Then came 16 months of specialized tracking training.
Five years after his introduction to the sheriff’s office, a real missing child needed him.
The Most Important Number Was Not Twelve
Twelve minutes made the story memorable.
It is the number that appeared in headlines.
It demonstrated how quickly a trained K-9 team could change the direction of a search.
Still, there was another number that mattered more.
One.
One missing child.
One family waiting.
One successful recovery.
The purpose of the training was not to generate an impressive time.
It was to bring someone home.
Rex Did Not Know He Had Made History For The Team
The sheriff’s office called it the tracking team’s first successful find.
Rex could not understand that distinction.
He did not know reporters would tell the story.
Nor did he understand that people would describe him as a “triple threat.”
For him, the sequence was more immediate.
A familiar command.
A scent.
A trail.
Work with Gray.
Then a reward.
That is enough.
Working dogs do not need human ideas about recognition to perform remarkable tasks.
Good training and a strong handler relationship can explain plenty.
Gray Knew What The Moment Meant
He had watched Rex grow from a young therapy dog into an animal capable of doing several jobs.
The tracking program had taken more than a year of focused work.
Then, on its first successful find, the outcome was exactly what everyone hoped for.
The missing child was located quickly.
She was unharmed.
Her family got her back.
After that, Rex did not need to follow another scent.
He could stay near the child instead.
A Pair Of Shoes Started The Final Twelve Minutes
That is the simplest way to remember what happened.
A 7-year-old girl had been gone for almost two hours.
Deputies were searching.
Then John Gray gave Rex her shoes.
The black Labrador identified the scent and went to work.
His movements helped deputies determine which way the child had traveled and where she had not.
The trail narrowed.
A nearby backyard came into focus.
Twelve minutes after Rex started tracking, deputies found her.
She was safe.
Then the dog whose nose had helped locate her returned to the first job he had ever been trained to do.
He stayed close enough to offer comfort.
Years of training had brought Rex to that afternoon.
First, he helped deputies find the child.
Then he got to be what he had been from the beginning.
A calm black Labrador beside a kid who had just been through a frightening day.
