"We're speaking with the boy today," FBI spokesman David Staretz said Sunday. "I know he's being interviewed by law enforcement, and we'll probably get a better idea of where he's been."
Cole's father, Robert Puffinburger, was a picture of relief at a news conference, as he smiled, cried and thanked police and neighbors for helping to bring Cole home.
"I'm just so glad he's safe," his father said.
Staretz would not comment further on what had happened to Cole in the four days since he was snatched from his mother's home by two men posing as police officers. Police have said they believe the abduction Wednesday was an attempt by drug dealers to send a message to the boy's grandfather.
A bus driver for the disabled discovered Cole walking alone on a residential street, said Jacob Snow, a general manager for the Regional Transportation Commission of Southern Nevada. The driver pulled over to see if he was OK.
"Cole approached the bus and asked the driver, 'Can you take me home?"' Snow said.
The bus driver, who did not want to be identified, took Cole onto the bus and contacted police, Snow said. The child told the driver and riders that he had been dropped off just a few minutes before.
Cole was in "extremely good condition" but was taken to University Medical Center as a precaution, Las Vegas police Capt. Vincent Cannito said. He was treated and released to his father's care early Sunday, hospital spokesman Rick Plummer said.
Robert Puffinburger and police had concentrated search efforts on a largely Hispanic neighborhood a few miles from where Cole was found. They posted fliers in English and Spanish with a photograph of the boy, a slight, smiling blond in glasses.
On Sunday, a blue painted sign in the front yard of the home from which Cole was abducted read, "Welcome Home Cole." The home appeared sparsely furnished, with a bare mattress on the living room floor. No one answered the door.
Robert Puffinburger would not comment on Cole's mother or her father, 51-year-old Clemens Tinnemeyer, who police say may have stolen millions from dealers involved in trafficking methamphetamine.
Tinnemeyer was scheduled to appear before a federal magistrate Monday in Riverside, Calif. He was arrested there Friday and was being held in nearby San Bernardino on a material witness warrant issued by a federal court in Nevada.
Las Vegas police didn't know whether Tinnemeyer had a lawyer. Police have declined to elaborate on what role he played in the drug operation or whether the kidnappers had been seeking a ransom.
Tinnemeyer described himself as a carpenter of 22 years when he and his wife, Diane, filed for bankruptcy in 2001. The couple live in an older Las Vegas neighborhood of weathered rambler-style homes on acre lots. A rooster crowed from a nearby yard Sunday.
The Tinnemeyers have lived there for close to 20 years, according to a neighbor who didn't want to be identified because he feared for his safety.
Until about two years ago, the house was busy with cars coming and going, he said. Cole was often at the home in the care of his grandmother, who works in a lunchroom of the local elementary school.
Tinnemeyer spent time in what he said was a recording studio behind the home, the neighbor said. He left in a motor home in May. The neighbor said he continued to see Diane Tinnemeyer daily but had not seen her husband since.
Messages left at a number believed to be for the Tinnemeyer home were not returned. A black pickup truck sat in the driveway Sunday, but no one came to the door.
Staretz said authorities continued the search Sunday for another "person of interest," a Mexican citizen identified as Jesus Gastelum.
Gastelum, who is in his mid-30s, is believed to be in Las Vegas or Southern California, police said. Another "person of interest" in police custody Saturday was not identified.