It sounded all too real. So real that the intended victim had no doubt that his teenage son had been kidnapped. "Someone had my son, who I had heard crying and screaming in the background, covering his mouth with a gun to him," said Jamey Heath, a Los Angeles music producer. The extortionist told Heath to immediately go to his bank and withdraw money if he wanted to see his 15-year-old son Nakh alive. What he didn't know at the time was that the call is part of an elaborate scheme targeting wealthy area codes around the United States. His son was actually safe. It's called virtual kidnapping and it is spreading. The extortion scheme is so effective that many terrified victims pay up. The callers convince victims that their son or daughter has been taken. Many follow demands to immediately drive to the bank and withdraw money. Anyone who answers the phone is a target, particularly a well-off businessman with a family. "The whole point of this for them is to make money fast, make as much money as possible," FBI Special Agent Erik Arbuthnot told CNBC.

Wealthy targeted

"It could happen to anybody," he said. "They're calling across the United States, and the FBI really doesn't want victims to feel ashamed in reporting it. We've seen police officers, police detectives, architects, doctors, attorneys, professional people have gotten these calls — truly feared that their loved one was kidnapped and have made the payment." And, according to the FBI, it's one of the most underreported crimes, because many people feel embarrassed it happened to them. Most surprisingly is where the calls are coming from. The FBI has traced most of them to inmates in Mexican prisons. "It was really an eye-opener for me," Arbuthnot told CNBC. "Because we have been tracking the phone records. We interviewed a lot of victims. A lot of the victims we've had to find from the phone records because they haven't reported it." While versions of the scheme have been around for about a decade, the calls changed from Spanish to mostly English three years ago. The Beverly Hills area got bombarded that summer as the criminals "literally called every single phone number in Beverly Hills to try to get more money," he said. Armed with victims' phone records, the FBI was able to trace the calls to Mexico and eventually to inmates using smuggled phones.

Inside a Mexican prison

Imagen, a Mexican broadcast network, aired a report in 2017 using hidden camera video inside a Mexico City prison that showed inmates casually making extortion calls out in the open. Layda Negrete, a senior researcher with the World Justice Project, an international human rights organization, said inmates initially targeted victims in Mexico, but then started calling the United States. "It's organized crime within the confines of the prison," she said. Around the clock, inmates pull off the scheme using phones they acquired from bribing guards. "There's a boss, and, every day for eight hours, there are people doing extortion over the phone. It has hierarchies and it's very well-established," she said. "The typical phone call, and these phone calls are now in English, come into the United States, and we're talking about thousands of phone calls over the last few years," Arbuthnot said. "You say 'hello' and you hear a screaming voice like you know 'help me mommy, I'm in trouble.'" The callers typically imitate a screaming child or even may use a recording of someone's voice. CNBC spent weeks reaching out to various government agencies and politicians in Mexico, including local officials in Mexico City, where most of the extortion phone calls are made, but no one would comment on what they are doing to stop the problem. The equivalent of the Internal Revenue Service would not comment and neither would the former secretary of Government for Mexico City, Patricia Mercado, who was also ran for Senate. CNBC also reached out to various officials at the attorney general's office, both federal and Mexico City police, and the National Security Commission and no one returned our request for comment. After being directed to the Embassy of Mexico, a spokesperson emailed CNBC, "This issue has not been raised by U.S authorities during our meetings regarding security and law enforcement."

Son was 'taken'

Jamey Heath got the call at home. "I hear this, 'daddy, daddy daddy, help,'" he said. "And I'm like, 'Nakh, calm down buddy, calm down.' It didn't occur to me that it could not be him. It was just him." "So this went on 30 seconds, a minute. Finally, I'm like: 'buddy, what's the matter, just calm down, just tell me what's up.' And then I hear him say 'they're gonna hurt me.' And I'm like, 'what, what are you talking about?' And then I hear someone cover his mouth and then someone grabs the phone and says, 'Is this Nakh's dad?' He says 'listen to me, listen to me closely. How you respond in the next 20 seconds determines whether or not you see your son again. I have your son.'"

Virtual kidnapping victim Jamey Heath and his 15-year-old son, Nakh CNBC

Then Heath was told to withdraw money out of his bank account, so he rushed to his car. All the while, he stayed on the phone with the man yelling at him. At the bank, he ran inside where employees saw that he was hysterical and took him to a room. Finally, his wife texted him that Nakh was safe. Still, Heath said he wasn't entirely convinced until he spoke to his son on another phone at the bank. "And then I realize that I've been scammed," Heath said. "But my adrenaline, for the last 30 minutes, my body had experienced that my son was kidnapped." While he didn't pay anything, many others around the country have withdrawn money from the bank and wired it to Mexico, Arbuthnot said. The funds – like the cellphones the inmates use to make the calls – are smuggled into the prison. In other versions of the crime, an accomplice in the U.S. picks up the money at a designated drop-off location. "It's really a perfect storm when the person is caught alone, and their daughter or son is not there, that's when you see the payment get made," he said.

Extortion call during class

Rebekah Pogue, an Orange County, California, teacher, was also convinced that her daughter, Abby, was kidnapped when she got a call in her seventh-grade classroom. It was a number she didn't recognize from Mexico, but she answered because she thought it may have been the pizza she had ordered for a lunchtime math class. "And instead of the pizza guy, I hear a young voice, sounds just like my 15-year-old daughter saying, 'mom, mom they have me, they have me,''' she said. "And she's borderline yelling, crying like hysterical." And like Heath, she said she believed it was her daughter screaming on the phone. "I don't know how to describe the feeling. But there was no doubt in mind that was her voice," Pogue said. "It was like an out-of-body experience. I can't move my hand from my ear and I'm panicked, but then I'm trying to stay calm enough to do whatever he tells me. I said, 'I will do whatever you tell me to do. Please, don't hurt my daughter.'"

Virtual kidnapping victim Rebekah Pogue CNBC

Panicked, she rushed out of her classroom. Along the way, other school employees were signaling her that they had called the police. With the extortionist still on the line, she told them to find her daughter. Jumping in her car, she drove to her bank. At a stoplight, she texted her husband frantically trying to find out if Abby was OK. As she pulled up to the bank, the caller demanded she go inside and withdraw as much money as possible. Suddenly, her daughter was on the other line. "And so now on my phone, pops up her picture because her picture is tied to her contact in my phone — and at that moment, I just break down. I am sobbing in the car in front of the bank because I have her on the phone." She hung up, and was met outside her car by a police officer. She said the extortionist actually called back, but ended the call after the officer started talking to him. The odds are that the extortionists won't get caught. There has been only one U.S. federal prosecution, which was in 2015 involving a Mexican national who was already in prison in Mexico on unrelated charges. The scheme covered more than 40 victims in several states. In Orange County, where Pogue was victimized, the sheriff's office said it receives between five and six reports a month related to the extortion scheme. CNBC contacted more than 40 police departments across the country, including those in the wealthiest ZIP codes and largest metropolitan areas, to see if they had received complaints. Thirteen police departments, including eight in California, plus those in Texas, Arizona, Massachusetts and Delaware have received complaints. "[We] receive virtual kidnapping [complaints] on a continual basis. Generally they have been targeting individuals that are wealthy," said Sgt. Max Subin of the Beverly Hills Police Department. The Delaware State Police had a sudden spike of nearly six calls earlier this year but Master Cpl. Michael Austin said the true number is probably higher. "A lot of them go unreported because it's sniffed out by the victim prior to it ... or people [who fall for the scheme] are too embarrassed." Other departments also report that calls are on the rise. "We are investigating some instances of virtual kidnapping. As for a rise, this is a relatively new trend, so in that respect, we are seeing more recently than before," said Sgt. Vince Lewis of the Phoenix Police. Even law enforcement officers have been victims. As a retired Delaware state trooper, Al Ament is one of the last people you'd expect to fall for a virtual kidnapping scam, which is a testament to just how convincing it really is. When he picked up the phone in March of this year, he heard a voice that sounded just like his 38-year-old son, who happened to be on a honeymoon abroad. "You don't know if it's real or not. You don't know if they've really kidnapped your family member or not," Ament said. The man demanded Ament pay $4,000 in exchange for his son, and Ament said he quickly lost his temper. "I used direct language: 'If you harm my son, then I will hunt you down.' The conversation escalated into screaming, and I got to a point where he hung up on me."

Wiring money to Mexico

Other victims like Valerie Sobel have wired thousands of dollars to Mexico. When Sobel received the call in August 2015, the man on the phone told her that they had already cut off her daughter's finger and that she had to pay up unless she wanted her in a body bag.

FBI Special Agent Erik Arbuthnot. CNBC