SAN FRANCISCO — For weeks, the United States government has said that the only way to open an iPhone used by a gunman in a mass shooting was to get Apple’s help, a position that set off a clash between the technology giant and law enforcement.

But remarks by a federal prosecutor in a court conference call on Monday and a letter from the F.B.I. director, James B. Comey Jr., published on Wednesday indicated a recent flurry of activity behind the scenes between law enforcement and other parties that have suggested methods to break into the phone.

Mr. Comey, in a letter to The Wall Street Journal, wrote that the case between Apple and law enforcement over opening the iPhone has stimulated people worldwide to try to get into the device.

And in a court transcript of a conference call on Monday with Apple’s lawyers and Sheri N. Pym, the federal magistrate judge presiding over the case, a Justice Department attorney, Tracy Wilkinson, said, “There have been a lot of people who have reached out to us during this litigation with proposed alternate methods.”