A US judge cancelled a high-profile hearing between Apple and the FBI set for Tuesday after the FBI made the surprise announcement it may have found its own way to hack an iPhone at the center of the legal dispute.
In a motion filed late Monday in federal court, government lawyers said that the day before, an "outside party" had shown the FBI a possible method for unlocking the iPhone 5c used by Syed Rizwan Farook, who with his wife killed 14 people in a terrorism attack December 2 in San Bernardino, California.
The government said it needed time to test the method, but that if it proved viable, "it should eliminate the need for the assistance from Apple" that had led it to a courtroom showdown with the world's richest company.
"We must first test this method to ensure it doesn't destroy the data on the phone, but we remain cautiously optimistic," US Department of Justice spokesperson Melanie Newman said in a statement to US media.
The court ordered Apple last month to write and install a new version of the device's operating system to bypass a security protocol that will destroy stored data after too many failed password attempts.
Apple chief executive Tim Cook has refused, saying the government is overreaching. He said the "back door" they propose is "too dangerous" to create because its existence could compromise the security of every iPhone equipped with such measures.
The FBI has countered that the data possibly stored on the device was a matter of national security, and that only Apple had the ability to help them get it.
The case has set off a national debate about the limits of governments' right to access digital data and of users' right to protect it.
While US lawmakers and the public appear divided on the issue, US President Barack Obama has sided with law enforcement, calling for compromise. Tech companies and privacy advocates have taken Apple's side against it.
The iPhone 5c belonged to Syed's employer, the local county health department.
Although Apple built the device, its security architecture makes it impossible for anyone - even Apple - to open it without the password programmed by Farook, who with his wife was shot and killed by police after the workplace shooting during a holiday party.
Apple mobile operating systems starting with iOS8 have an auto-erase function that destroys data if the phone is forced. Farook's phone was running the next version of the software, iOS9.
In the dispute, the FBI had argued that the only way to access data on the phone was for Apple to write and force-install a new operating system without the security protocols.
Critics, including some in the US Congress, had publicly wondered why the FBI's technical experts couldn't find a way to break into the device themselves.
Others had suggested the FBI should ask for help from the National Security Agency (NSA), the intelligence agency that employs some of the nation's top hackers.
It was unclear who had proposed the potential solution. In court papers, the government said only that amid the controversy it had continued to conduct its own research into how to break into the device, and that others "outside the government" had been in touch offering help.
Oral arguments at the federal district court in Riverside, California, had been scheduled to take place Tuesday. The government will file a status report April 5 instead.