BRIGHAM CITY, Utah (KTVX) — A missing and endangered 17-year-old Chinese foreign exchange student has been located and returned to his family after an alleged “cyber kidnapping,” according to Riverdale City Police.

Kai Zhuang had been reported as kidnapped on Dec. 28 after his parents in China received a ransom demand for his safe return. The parents contacted school officials in his host city of Riverdale, Utah, where police said even the family he had been staying with did not know he was missing.

Authorities originally believed Zhuang may have been forcefully kidnapped, However, in a press release Sunday night, Riverdale Police explained they had determined he was a victim of a “cyber kidnapping.”

On the night before his disappearance, Zhuang’s host family in Riverdale told police he had been home and nothing seemed out of the ordinary. They heard him moving around in the early morning hours of Dec. 28, but again had no reason for concern. Police determined Zhuang left the house on his own.

As police, the FBI, and the U.S. and Chinese embassies began to investigate, they learned Zhuang’s family had transferred around $80,000 to bank accounts in China after receiving threats from the kidnappers. The family had also received a photo of Zhuang, “and it appeared he was being held captive and was in danger,” according to Riverdale Police.

Authorities explained that FBI agents working the case briefed investigators on several other recent similar cases they were referring to as “cyber kidnappings,” in which kidnappers target foreign exchange students. Chinese exchange students have been a specific target in these cases.

The alleged kidnappers threaten both the family back in China and the student in their host country by telling each that the other is in danger. They demand ransom from the family while telling the student to isolate themselves, monitoring them via cell phone, including FaceTime and/or Skype sessions. They convince the victim to take actions such as taking a photograph that makes it look like they’ve been held captive.

“The victims comply out of fear that their families will be harmed if they don’t comply with the cyber kidnappers,” said the Riverdale Police press release. “The cyber kidnappers continue to extort the family by using fear tactics, photos and voice recordings of the victim, leading the family to believe the kidnappers are with the victim, causing them harm.”

Riverdale Police said their investigation started with warrants for phone records, bank accounts, and transportation companies. Police looked at neighborhood surveillance footage to try to establish a timeline.

With the help of drones and aerial searches — as well as investigators analyzing purchases, looking at phone records, and pinging Zhuang’s phone — police said the boy was found Sunday in a tent on a mountainside near Brigham City, about 25 miles north of Riverdale.

Police said Zhuang was “very cold and scared,” and “relieved to see police.” He had no heat source in the tent and was cleared of any potential medical dangers, including hypothermia. He only wanted to speak to his family to make sure they were safe “and requested a warm cheeseburger.”

“We believed the victim was isolating himself at the direction of the cyber kidnappers in a tent,” stated Riverdale Police.

Police explained that about a week before his disappearance, police in Provo found Zhuang attempting to go camping nearby, but they were worried for his safety and arranged to have him taken back to Riverdale. Though Zhuang did not tell Provo Police at the time, investigators say the alleged cyber kidnappers were already manipulating him.

Additional details about the alleged cyber kidnapping have not yet been released, and investigators are continuing to search for the suspect or suspects involved.

Riverdale Police warn that if you are approached by cyber kidnappers, you should not give them any money and you should contact authorities immediately while stopping all communication with the criminals.