Naveed Akram and his father Sajid Akram are alleged to have killed 15 people at a Hanukkah event on December 14, Australia’s worst mass shooting in almost three decades.

Police have previously said the men were inspired by Daesh, with home-made flags of the militant group found in their car after the attack, and a month-long trip by the pair to a Philippines island previously plagued by militancy was a major focus of investigation.

But on Tuesday, Australian Federal Police Commissioner Krissy Barrett said there was no indication the men had received formal training on the November trip to Mindanao in the Philippines.

“There is no evidence to suggest these alleged offenders were part of a broader terrorist cell, or were directed by others to carry out an attack,” Barrett told a news conference.

She added that the findings were an initial assessment, and authorities in Australia and the Philippines were continuing their investigation.

“I am not suggesting that they were there for tourism,” she said, referring to the Philippines trip.

Sajid Akram was shot dead by police during the attack, while his son Naveed, who was also shot by police, was charged with 59 offences after waking from a days-long coma earlier this month.

Naveed Akram faces charges ranging from 15 counts of murder to terror and explosives offences.