The distress call came Sunday around 1pm: emergency in Beverly Hills. Someone was being held hostage at “Simon Cowell’s”. The victim, reported a female caller, was tied up with duct tape inside a bathroom at the brash British ‘X Factor’ judge’s hillside mansion.

A similar call reached the Los Angeles County Sheriff’s Department on October 10 before 2am. Someone inside a gated Calabasas mansion reported shots fired and said the gunman was threatening residents, making clear he’d put police in his cross hairs when they showed up. Unbeknown to sheriff’s deputies, that mansion belonged to the most famous teenager on the planet, Justin Bieber. Multiple squad cars were scrambled and heavily armed deputies arrived. They swept Bieber’s residence and two others on the street before discovering it was all a hoax. The pop star, on tour at the time, was nowhere near the mansion.

Cowell was home when Beverly Hills police arrived at his residence. But there was no hostage negotiation, no armed standoff, nor were any arrests made.

“The dispatcher believed the call was a hoax,” said Lincoln Hoshino of the Beverly Hills Police Department.

Count Bieber and Cowell as the latest high-profile victims of “swatting,” a fast-growing phenomenon masterminded by anonymous mischief-makers who alert police to a bogus crime situation, prompting a tactical response — sometimes by SWAT officers — that involves a high-risk search for phantom assailants. Several officers have already been injured responding to such calls, and officials, including Los Angeles Police Chief Charlie Beck, fear that it’s only a matter of time before events turn deadly. Within Hollywood, in an era when breaches of celebrity privacy have never been more invasive — by paparazzi, hacker journalists or even websites that provide detailed information about stars’ homes and street addresses — the pranks have taken on troubling dimensions.

“Swatting is a very real problem for those in the public eye,” said Blair Berk, a criminal lawyer who has represented stars including Mel Gibson, Kanye West and Lindsay Lohan.

“It is only a matter of time before someone dies because of this stupidity.”

What started a decade ago as a malicious prank among computer gamers is quickly evolving into a Grade-A crisis for law enforcement nationwide, encouraging new legislation aimed at stiffer punishments for swatters as well as redoubled attempts to defeat the “spoofing” technology that enables such cyber-troublemaking. Chief Beck acknowledged that swatting has stretched the LAPD’s emergency response capacity while also endangering victims by placing them in potential confrontation with police firepower.

“It not only draws public safety resources away from real emergencies, it places people at significant risk by the dispatch of armed police officers,” said Beck. “Our big fear is that [swatting] will become more prevalent.”

Chief Bill McSweeney of the Los Angeles Sheriff’s Department says that the most sophisticated swatting manoeuvres involve tricking caller ID so that a 911 call can be registered as having been placed from inside the very household being swatted.

Investigators say a 911 call reporting an armed home invasion that sent firefighters plus a dozen police officers swarming down on Miley Cyrus’ unoccupied Studio City home in August may have originated from a cellphone, then bounced over several internet providers to hide its origin.

‘Spoofing’ technology

Bieber’s swatting was called in through a device that allows hearing-impaired callers to send messages over the phone. That kind of “spoofing” technology — an elaborate computer fake-out that falsifies data, obscures a person’s digital identity and location and can even make a man’s voice sound female — is legal and widely available on the web.

“Any time you use a telephone or a computer, there is an electronic trail,” said Philip Lieberman, founder and president of Lieberman Software, which specialises in computer security. Phone carriers and internet providers monetise every digital communication and have a vested interest in tracking caller origination.

“It is virtually impossible not to get caught unless they have a heavy level of sophistication.”

But even with the advanced software used by the LAPD, tracing spoofed calls or teletexts can be difficult.

“If these calls originate with a throwaway phone,” McSweeney said, “sometimes those are hard to track.”

Days after Cyrus was swatted, someone claiming to be a woman locked inside a closet at Ashton Kutcher’s Lake Hollywood residence sent a text to 911 reporting that shots had been fired and individuals identified as “Russian men” were robbing the house. Kutcher was shooting his TV show ‘Two and a Half Men’ at the time but dozens of heavily armed officers from several LAPD divisions and a helicopter rushed to the scene and detained three workmen at the property. The incident came with a steep price tag for the city: $10,000 (Dh367,323.)

Investigators found evidence that the emergency caller may have had Kutcher’s house under surveillance, said two people familiar with the investigation who requested anonymity because the investigation is ongoing. They cited the caller’s proprietary knowledge of how many people were inside the home before law enforcement arrived. No one has been prosecuted in any of the celebrity swatting cases. But because of similarities in the Bieber, Cyrus and Kutcher incidents, police officials suspect the same person may have swatted the three stars — all of whom, coincidentally or not, have hosted the MTV prank comedy show ‘Punk’d.’

Kevin Kolbye, assistant special agent in charge of the Dallas-Fort Worth FBI office, began fielding swatting probes in 2007. He views the phenomenon’s rapid growth in recent years as a dangerous replacement for a time-honoured practical joke.

“You no longer call pizza [to someone’s house] like in the old days,” said Kolbye. “Instead, the young generation are getting their kicks putting a lot of people at risk. We’ve already had a couple of heart attacks and an officer hurt in a collision responding to scene.”

The intent there was to cause harm. The other angle is swatting degrades the police’s ability to trust 911. Currently, the FBI is investigating more than 100 active swatting cases nationwide. Chief McSweeney said the Los Angeles County Sheriff’s Department has taken on more than a dozen swatting cases in the last year involving online gamers, celebrities and bloggers.

One major stumbling block to police efforts, however, is California law. At present, making a false police report is still only a misdemeanour. But departments across LA County are beginning to realise that many jurisdictions are wasting valuable resources on swatting call-outs.

“We are going to approach the Legislature with the idea of making swatting a felony,” McSweeney said.

Senator Ted Lieu oversees a district that includes such celebrity-studded neighbourhoods as Beverly Hills, Bel-Air and Pacific Palisades. He is looking into proposing legislation that would make it easier for district attorneys to make swatting a felony offence.

“There may be other ways to do it in which you wouldn’t need a law,” Lieu said. “But if they can’t fix it — if they can’t figure out a way to easily trace the people who make these very dangerous 911 calls — I would introduce a bill to try to mitigate the problem. The issue is, people have figured out how to do this,” Lieu said, “and it’s only going to get worse unless you can put some consequences in place.”