Prosecutors say Cummins planned to cross the U.S. -Mexico border then seek refuge with his 15-year-old former student, Elizabeth Thomas, in Central America.
Cummins is facing a federal charge of transporting a minor with intent to engage in criminal sexual activity.
The girl's disappearance, according to police, came more than a month after a student reported seeing Cummins kiss her.
The Tennessee teacher was arrested Thursday and the teen was recovered in Northern California after a nationwide search. The 15-year-old high school freshman is apprehensive about being around people, said family members, who have kept conversations light and not peppered her with questions about her 39-day ordeal as she tries to heal. According to the federal prosecutors, Cummins admitted to complex efforts to avoid capture during his 38 days on the run, including traveling back roads through nine states, using disguises, disengaging the Global Positioning System on his wife's Nissan Rogue and staying in motels with lax check-in procedures and communes.
Cummins admitted he had gotten a small watercraft and conducted a test run from San Diego to Mexico, where he planned to take the teenager, according to a federal complaint.
He is scheduled to be arraigned in federal court in Sacramento, California, on Monday.
The US Attorney's Office is requesting that Cummins remain detained pending trial in the Middle District of Tennessee. An AMBER Alert was issued across the state of Tennessee the following day, and Cummins was added to the TBI's Top 10 Most Wanted list on March 17.
Cummins was immediately taken into custody.
Whatley said that after meeting the teen for the first time, he was "taken back at who she is". That charge carries a statutory mandatory minimum sentence of 10 years, but Cummins could be sentenced to as much as life as prison, according to the USA attorney's office. In both cases, the rooms only had one bed. "You don't know what to say, because she's been through something very traumatic".
A short time later, investigators say, he drove to the Shoney's restaurant, where Elizabeth had been dropped off by a friend.
Friday afternoon, Mark Gwyn, the director for the Tennessee Bureau of Investigation, said when asked if Cummins was helped by anyone, "It's an ongoing investigation".
Surveillance footage captured the pair at a Walmart in Oklahoma.
Elizabeth Thomas, the Tennessee teenager kidnapped by her teacher, was withdrawn and thinner after she was rescued, family members said Monday.
Elizabeth's father, Anthony Thomas, told ABC News after Elizabeth was found, "She may not be exactly. the person she was because there's a lot of experiences she's had".