The security camera footage shows the pair walking into the store and talking. It also shows the young girl, at times, standing alone near the counter.
It would be the last taste of freedom for a man who, within hours, was surrounded by police.
Duncan, a registered sex offender who once told a therapist he had raped 13 boys by the time he was 16, had broken into the little girl's home in the US state of Idaho wearing night-vision goggles two months earlier.
Video provided by the owner of the convenience store shows Shasta Groene and her abductor Joseph Edward Duncan hours before she was rescued. Duncan had murdered her entire family. Photo / AP
There, he had tied up Shasta's mother, Brenda Groene, Brenda's boyfriend, Mark McKenzie, and Shasta's brother, Slade, aged 13, before beating them to death with a hammer.
Not done there, Duncan abducted Shasta and her brother, Dylan, nine, before taking them to the woods of Montana where he shot the young boy in the head at point-blank range.
Shasta suffered for months at the hands of her sadistic captor as he raped her repeatedly.
But his decision to take Shasta to a convenience store and a Denny's restaurant proved his undoing.
Employees at the restaurant recognised the little girl and called authorities who arrived with headlights off and guns drawn to take the killer into custody.
Two days after his arrest, authorities found human remains in the Lolo National Forest. They were later identified as those of Dylan Groene.
Duncan, who had raped Shasta Groene repeatedly for two months, was captured later in the day after workers at a restaurant recognised her from missing posters. Photo / AP
Duncan was sentenced to death by a Federal Court but died this week from brain cancer prior to his execution.
Shasta, now in her mid-20s, spoke of the relief she felt at Duncan's death.
"For so long I have been struggling with hate towards that man. Today, I woke up feeling like my soul was finally free," she said in a written statement.
"I hope other people affected by Joseph Duncan were able to wake up feeling the same way."
Shasta Groene stands cross-armed in a convenience store in Kellogg, Idaho on July 1, 2005, hours before she was rescued. Photo / AP
After his arrest, Duncan admitted to other grisly crimes, including the murder of a young boy from Beaumont, California named Anthony Martinez.
Duncan said he used the sick tactic of offering the 10-year-old boy $1 to help him find a missing cat before forcing him into a car at knifepoint.
Martinez's body was found naked and buried under rocks at Berdoo Canyon near Palm Springs 15 days later, the Los Angeles Times reports.
At the time, no arrests were made. But Duncan admitted to the gruesome murder when his run of crimes had come to an end.
Martinez's younger brother Marcos said in a statement, "There is less evil in the world. Nothing can bring my brother back, but now Duncan can never hurt anyone ever again."
