TOMS RIVER, NJ — A Plumsted teenager accused of plotting to shoot up his high school graduation is now facing an additional charge of terrorism, Ocean County Prosecutor Joseph D. Coronato announced Tuesday.

The charge of terrorism was lodged against Matthew Vanderbeek, 19, of Plumsted, after the prosecutor's office received written authorization from New Jersey Attorney General Gurbir Grewal, said Al Della Fave, spokesman for the prosecutor's office. Terrorism is a first-degree offense punishable by 30 years to life in prison. Vanderbeek already is being held on a third-degree charge of terroristic threats with a threat to kill and a second-degree charge of attempting to possess a firearm for an unlawful purpose, both of which were filed when Vanderbeek was arrested June 19, Della Fave said. (READ MORE: Teen Planned Shooting At New Egypt HS Graduation: Authorities)

Authorities allege Vanderbeek was trying to obtain a gun to kill students and staff during the New Egypt High School graduation, which was held last Thursday. In the probable cause affidavit, authorities allege Vanderbeek had told other students he wanted to shoot up graduation, and asked a schoolmate to take him to a sporting goods store in Jackson so he could buy a firearm.

He also allegedly told other students he had dyed his hair red because of an accused school shooter, which appears to be a reference to the 19-year-old accused of killing 17 students and staff members at Marjory Stoneman Douglas High School in Parkland, Florida, in February, according to the affidavit. (READ MORE: Plumsted Teen Threatened Shooting At 2nd School: Affidavit) Vanderbeek also allegedly had made threats to shoot up the graduation ceremony for the Ocean County Vocational Technical Schools' Brick center, according to the affidavit. That alleged threat resulted in Vanderbeek being suspended from school at New Egypt High School and being permanently removed from the vocational school, the affidavit said.

In addition to allegedly saying he was planning to shoot people at the New Egypt graduation, Vanderbeek is alleged to have made a pair of chilling posts on Snapchat that talked about guns and violence, including one referencing a Biblical passage that talks about the end of the world.

The threat was reported to school administrators the morning of June 19; Detective Brant Uricks from the prosecutor's office and Detective Anthony Ringle from Plumsted investigated and arrested Vanderbeek later that day after searching his home on Hyacinth Court to check for weapons and additional evidence of the crime, including communications made via phone or computer.