Federal investigators believe bomb threats against Jewish centers and schools in the U.S came from people using sophisticated technology to shield their identities, BuzzFeeed News reports.
Those responsible "are leveraging technologies that have made the investigation more challenging." Paul Goldenberg, national director for Secure Community Network, a homeland security initiative focused on the Jewish community, told BuzzFeed News.
Investigators suspect that some of those calling in the threats were using "spoofing," Goldenberg told the website. When spoofing is used, a call appears to come from a friendly or known source, when it is actually coming from someone else, BuzzFeed noted.
CBS News reported the calls appear to be coordinated.
But The New York Times said that a single person may be making the threats using an internet calling service.
And BuzzFeed noted there have also been reports that those making the calls are also using "voice masking technology."
Meanwhile, Goldenberg said he has never seen anything like the wave of bomb threats hitting the Jewish community centers.
"You can't even compare it," Goldenberg said. "I have been in business for two decades, and we have never seen a number at this level in a short period of time."