The surprise move appears to vindicate Apple's argument, which is that the US Government had not exhausted all available means to recover information from the phone.
It also stands in contrast to assertions made by FBI Director James Comey who earlier this month testified that bureau officials "have engaged all parts of the U.S. government to see does anybody have a way, short of asking Apple to do it," to unlock Farouk's phone. "And we do not," he said.
Similarly, FBI supervisory special agent Christopher Pluhar said in a court filing that the bureau had "been unable to identify any other methods feasible for gaining access."
"Our top priority has always been gaining access into the phone used by the terrorist in San Bernardino," said DOJ spokeswoman Melanie Newman in a statement Monday. "With this goal in mind, the FBI has continued in its efforts to gain access to the phone without Apple's assistance, even during a month-long period of litigation with the company. As a result of these efforts, an outside party demonstrated to the FBI this past weekend a possible method for unlocking the phone."
She added: "We must first test this method to ensure that it doesn't destroy the data on the phone, but we remain cautiously optimistic. That is why we asked the court to give us some time to explore this option. If this solution works, it will allow us to search the phone and continue our investigation into the terrorist attack that killed 14 people and wounded 22 people."
Last month, the Justice Department announced it had obtained a court order under the All Writs Act to force Apple to create software to disable a phone security feature so the FBI could try its hand at unlocking the device by cracking a numeric password.
Apple argued that the law the government cites does not permit a court to force it to do such a thing, that doing so would violate its constitutional rights, and that a ruling in the government's favor would set a precedent that could weaken overall device security and privacy for users around the world.
The government argued that the law did authorize the court to direct Apple to provide the assistance and that Apple, which creates its own software, was the only party that was in a position to help.