The FBI has unlocked the San Bernardino gunman's iPhone without Apple's help, the US Justice Department says, ending a court battle that had significant implications for privacy and security.
Apple had been resisting a court order issued last month requiring it to write new software which would allow officials to access Rizwan Farook's smartphone.
But officials on Monday said the device had been accessed independently and asked for the order to be withdrawn.
Farook and his wife, Tashfeen Malik, killed 14 people in San Bernardino in December.
They were later shot dead by police. US officials said Malik had pledged allegiance to the so-called Islamic State on social media on the day of the shooting.
Last week, prosecutors said "an outside party" had demonstrated a possible way of unlocking the iPhone without the need to seek Apple's help.
A court hearing with Apple was postponed at the request of the justice department, while it investigated new ways of accessing the phone.
At the time, Apple said it did not know how to gain access, and said it hoped that the government would share with them any vulnerabilities of the iPhone that might come to light.
On Monday, a statement by top California federal prosecutor Eileen Decker said investigators had received the help of "a third party", but did not specify who that was.
Investigators had "a solemn commitment to the victims of the San Bernardino shooting", she said.
"It remains a priority for the government to ensure that law enforcement can obtain crucial digital information to protect national security and public safety, either with co-operation from relevant parties, or through the court system when cooperation fails," the statement added.