ST. GEORGE, Utah - A Utah teenager accused of trying to blow up a homemade backpack bomb at school after looking at Islamic State propaganda online will stand trial as an adult on two felony counts, a judge decided Thursday.

Authorities have said 16-year-old Martin R. Farnsworth wanted to cause fear after viewing the propaganda.

The device he is accused of bringing March 5 to Hurricane High School in St. George did not explode and no one was hurt.

He is charged with attempted murder and using a weapon of mass destruction, each charge punishable by at least five years and up to life in prison, KUTV in Salt Lake City reported .

Investigators found no connections between the boy and the terror group.

Prosecutor Angela Adams told the Deseret News that bringing the case to adult court would allow authorities to supervise Farnsworth longer if he is convicted.

In the juvenile system, defendants can only be held until 21. Prosecutors argued the teenager hasn't shown remorse and would do it again if he wasn't in a secure facility.

Defence attorneys say Farnsworth was bullied and suffers from a form of autism that keeps him from understanding the effects of his actions.

The Associated Press does not typically identify juveniles accused of crimes, but Farnsworth has been certified to face trial as an adult.

He earned his Eagle Scout award at 13 and got good grades in school but has few close friends and is seen as awkward, his lawyer Matthew Harris has said. Harris wanted the case to stay in the rehabilitation-focused juvenile system.

He told the Deseret News on Thursday it was difficult to read Farnsworth's reaction to the judge's decision to send the case to adult court. The boy's family is concerned about his well-being but understands the charges are serious, he said.

Farnsworth was also accused of using spray paint to write about ISIS on a wall at the school in February. In that case, police have said he also cut up an U.S. flag and replaced it on a flag pole with a homemade ISIS flag.

He will be tried as a juvenile on misdemeanour graffiti and abuse of a flag charges in that case.

He has not entered a plea in either case.

News from © The Associated Press, 2018