A Vermont teenager who's accused of plotting a shooting spree at his former high school had spent time at a Maine treatment facility.

18-year-old Jack Sawyer had just recently returned to Vermont, reports the BDN, after spending time at Ironwood, a treatment facility in Morrill, Maine. According to the facility's website, the program works to 'encourage residents to become more self-directed, responsible, and emotionally mature." Sawyer kept a journal that included lists of the guns and ammunition he needed to complete his plans. The AP reports the journal also included the teen's thoughts on his own mental health struggles, thoughts of suicide, and love of his family.

Police say Sawyer had allegedly planned to shoot up Fair Haven Union High School, and wrote in his 'Journal of an active shooter' that he planned to kill as many people as possible. His plot included scoping out the school resource situation from the parking lot and then he would 'let loose his anger and hatred.'

A girl who attended Ironwood with Sawyer tipped off police to his suspected plans after he revealed them via online message, thwarting what could have been a deadly attack. On Friday, he pleaded not guilty to charges of attempted aggravated murder and other offenses.