Despite piles of incriminating evidence, including a checklist and a timeline for the attacks, the mother of 17-year-old Grant Alan Acord who planned to stage a bomb attack on his school said the youth is mentally sick.

"My heart goes out to everyone affected by Grant's struggle with PANDAS, a rare form of OCD (Obsessive Compulsive Disorder). I grieve for my son, but understand and support the efforts of law enforcement to keep our beloved community safe. This is a challenging and confusing time for everyone who knows Grant. I will have no further comment while I wait with the rest of you to see what unfolds," mother Marianne Fox said in a statement on Monday evening, released though a family attorney.

Read: American Oregon Teen Faces Attempted Murder Charges on Planning to Stage Bomb Attack in His School

Identified as Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus, the Obsessive-Compulsive Disorder Foundation Web site said two of the possible symptoms of persons with PANDAS are sudden unexplainable rages and personality changes.

Mr Acord had also apparently told of some classmates about his bomb inventions.

"You know, I didn't think much of it, 'cause he's kind of a strange kid," an unidentified classmate was quoted by the AP. "So I wasn't surprised he had some strange hobbies, you know?"

The way another classmate described Mr Acord was that it seemed to him the Oregon teen was just bragging that he could make bombs. "It wasn't like, 'Oh, I'm making bombs. I'm gonna blow stuff up.' "

Both classmates thought Mr Acord does not mean to inflict damage.

However, court documents obtained by the Corvallis Gazette-Times say otherwise. According to the Summary of Probable Cause document signed by Albany Police Detective Mike Wood, Mr Acord, in carrying out his alleged plan, would shoot and throw bombs inside the school, announce "the Russian grim reaper is here" and then kill himself before a SWAT team engages him.

Mr Acord even had a list of 'Current Stock (Items I'll Take)' once he executes his bomb massacre plan.

On Tuesday, law enforcement agencies formally charged Mr Acord with attempted murder and possession of a destructive device. He will be tried as an adult. Appearing in court via closed-circuit television from a withheld secure location, the American teenager did not enter a plea deal. Bail has been set at $2 million. He is scheduled to go back to court on June 4.