From left, National Security Agency Director Adm. Michael Rogers, FBI Director James Comey, Director of the National Intelligence James Clapper, CIA Director John Brennan, and Defense Intelligence Agency Director Lt. Gen. Vincent Stewart, participate in the Senate Intelligence Committee's hearing on worldwide threats, Tuesday, Feb. 9, 2016, on Capitol Hill in Washington. (AP Photo/Alex Brandon)The cell phone of one of the San Bernardino killers is still encrypted, despite the best efforts of mobile forensics experts to “crack” it, the FBI director James Comey told a Senate subcommittee on Tuesday.

The dangers of communications “going dark” is shown in the Dec. 2 terrorist attack at the California social-services agency, Comey told the Senate Intelligence Committee’s annual Hearing on Worldwide Threats.

“We still have one of those killers’ phones that we have not been able to open,” he said. “It’s been over two months, we’re still working on it.”

Tashfeen Malik, a Pakistani woman here on a visa, allegedly killed 14 people and wounded 21 others in the slaughter coordinated and carried out with her husband, Syed Farook. The slaughter took place at Farook’s workplace, the Inland Regional Center, and the couple was chased down and killed in a shootout roughly two hours later.

Of particular interest to detectives is a window of approximately 18 minutes, in which, authorities cannot account for the two killers’ whereabouts.

Mobile forensics experts like those at Cellebrite described the landscape of the industry in extended interviews with Forensic Magazine late last year. Experts have said that Apple and Blackberry devices are among the toughest to crack. Apple has even said that it cannot breach its own security measures to get into the latest iPhones when asked, experts said. BlackBerry has been known to provide some of the most secure government phones: including reportedly President Barack Obama’s.

READ MORE: Data Encryption: A Growing Concern in Mobile Forensics

Another case cited by Comey was the unsolved murder of Brittney Mills, a 29-year-old Louisiana woman who was eight months pregnant at the time of her death last year. Investigators have publicly said they believe the person who shot her was someone she knew – but they have not yet succeeded in getting past the encryption on her Apple phone which may provide crucial evidence in the case.

“They still can’t open it,” said Comey. “The case remains unsolved.”

Federal authorities including U.S. Attorney General Loretta Lynch say they don’t want an always-accessible “back door” – but they do want the ability to get access where the law provides.

“We are asking to work with Silicon Valley and the tech industry to make sure that, as we preserve encryption, we also preserve what we currently have — which is the ability for companies to respond to law enforcement warrants, court-ordered, court-authorized requests for information,” Lynch reportedly said.
The FBI Director told Senate subcommittee he was sometimes confused about “back doors” and accessibility of the technology for individual devices. But he said he wants companies to be able to open up the devices when the law asks them to.

“I’d like people to comply with court orders, and that’s the conversation we’re trying to have,” said the FBI director. “This is something I hear about all over the country… It is a big problem for law enforcement.”

A new report by the Berkman Center for Internet and Society, a Harvard think-tank, released a report called “Don’t Panic” last week which contends that law enforcement concerns are overstated.