San Francisco, Feb 20 (IANS): The US Department of Justice (DOJ) alleged that there was brand marketing strategy behind the refusal by Apple, a technology company in Silicon Valley, to help access the phone of a terrorist killer.

The DOJ on Friday filed a motion at a court in the US where Judge Sheri Pym on Tuesday ordered Apple to provide specialised software to hack into the phone of Syed Farook, XInhua reported.

Farook, with his wife Tashfeen Malik, was responsible for killing 14 people on December 2 last year in San Bernardino, California.

In the 35-page document, the DOJ included as an "exhibit" the three-page statement by Apple chief executive officer Tim Cook, which was posted on Wednesday to argue against Judge Pym's order.

Cook called the order, at the request of the Federal Bureau of Investigation (FBI), "an unprecedented step" threatening the security of Apple customers.

In its response, however, the DOJ said Apple's current refusal to comply with the court's order "appears to be based on its concerns for its business model and public brand marketing strategy."

It went to the length to say Apple "appears to object based on a combination of: a perceived negative impact on its reputation and marketing strategy were it to provide the ordered assistance to the government, numerous mischaracterizations of the requirements of the (court) order, and an incorrect understanding of the All Writs Act."

Under the US law, the All Writs Act, the law Judge Pym applied in issuing her order to Apple, authorizes the US federal courts to "issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principal of law."

FBI investigators, already accessible to call logs and other information from a mobile phone service carrier, told Pym earlier that without passcode they were unable to look into an iPhone 5c used by Farook.

It was a work phone owned by San Bernardino county, where Farook worked at the public health department.

The FBI therefore requested Apple's help to bypass a security feature that erases data in the smartphone after 10 unsuccessful unlocking attempts.

Cook acknowledged that the FBI asked for help from Apple in the days following the San Bernardino attack and his company has provided data in its possession.

Noting that Apple's assistance was necessary, the DOJ said technicians from both Apple and the FBI agreed that they were unable to identify any other methods feasible for gaining access to the "currently inaccessible data" on the phone.

It listed in footnotes four suggestions discussed between Apple and the FBI, including attempting an auto-backup of the phone with the related cloud service account at Apple and obtaining previous back-ups of the device.

Despite one senior Apple executive's defence on Friday that the company's refusal was about principles, rather than marketing, the DOJ pointed out that Apple "has consistently complied with a significant number of (court) orders."

The company reportedly unlocked at least 70 iPhones at federal investigators' requests between 2008 and 2015.

At a court hearing last year, Assistant US Attorney Saritha Komatireddy said Apple "had an established procedure to routinely take any of these requests, comply with them, processing them."

While trying to compel Apple to comply with the latest court order and provide the software needed, the DOJ said it would allow Apple "to retain custody of its software at all times" and "the software never has to come into the government custody."

A hearing on the case at the US District Court in Central California has been scheduled for March 22.