The FBI is trying to crack open another password-locked iPhone, this time belonging to Dahir Adan, the perpetrator of a knife attack on a Minnesota mall in which 10 people were stabbed.

At a press conference on Thursday, special agent Rich Thornton said that the FBI was “in the process of assessing our legal and technical options to gain access to this device and the data it may contain”, according to Wired.

Adan was shot and killed by police who attended the scene, and Isis later used social media to claim credit for the attack describing him as a “soldier of Islamic State”.

Thornton said that the FBI had “analyzed more than 780 gigabytes of data from multiple computers and other electronic devices” and is “conducting an extensive review of his social media and other online activity”.

“We continue to review his electronic media and digital footprint,” Thornton said.

The FBI has not yet filed a lawsuit against Apple, it said. But the case echoes the FBI’s attempts to access an iPhone belonging to Syed Farook, the San Bernardino shooter, in February.

In that case, the agency went to court to try to compel Apple to write a backdoor system which would allow it to bypass the phone’s four-digit password. The iPhone wipes all data if an incorrect password is entered a number of times.

But the case was eventually dropped because the FBI found its own way into the phone. Director James Comey said the FBI had paid about $1.3m for the hack, though it was not known where they purchased it. It was later speculated than an Israeli security firm was behind the hack, while a separate researcher in Cambridge also claimed to have found a method of bypassing the passcode.

The FBI has not disclosed whether Adan’s phone is the iPhone 5C, the same model as Farook’s, which would mean the FBI could use the same technique to bypass the password and access the phone. Later models of the iPhone added a “security enclave”, a piece of hardware that will have made it harder to bypass the password.

Adan was reportedly en route to buy a new iPhone, his family have said. He was a resident of St Cloud, Minnesota, which is estimated to have the largest Somali community in the US. Both the local police chief and Minnesota’s governor have expressed concern at a possible backlash against the local community.