An investigation into alleged threats made by a teenager against the South Australian public is expanding, with federal police conducting searches at multiple locations linked to the accused.

The investigation yesterday led to the arrest of an 18-year-old. 

“Probably the most complex and significant case I’ve ever received a briefing on,” Premier Peter Malinauskas said.

“This was a major investigation, it was technically extremely complicated.” 

The teenager is accused of sending emails threatening staff and students at Glenunga International High School. 

It is also alleged that he threatened to attack Gather Round, the Adelaide Fringe Festival, and the state’s Jewish community, unless he was given $23 million in bitcoin and cash. 

Police have not confirmed whether this or next year’s Gather Round was allegedly targeted.

While the investigation is ongoing, police believe the immediate threat has been contained, and the 18-year-old will remain behind bars until at least December.

Parents and students at Glenunga International High School have expressed concern following the revelation of the alleged threats, which included bombing, knife attacks, and the use of a vehicle. 

“It is very concerning, we want to make sure the kids go to school and come back home safe,” parent Rosemary Khilnani said.

The school issued a letter to parents, expressing gratitude to police for their work in ensuring the safety of the school community. The letter stated that the school would continue to operate as usual.

Security measures remain in place at the school.