A 20-year-old Hawaii man was arrested for allegedly creating chemical and explosive weapons in a plot to destroy residential and commercial targets on Oahu.
Ethan Sandomire, of Honolulu, was indicted by a federal grand jury on Wednesday on charges of possessing and attempting to possess the chlorine-gas weapons and an unregistered destructive device.
Mr Sandomire planned to destroy a "centrally located", 40-storey apartment building with about 450 residential units, several commercial units and a multi-level grocery store, according to the indictment.
Federal Bureau of Investigation special agent Eli S Miranda said Mr Sandomire went to great lengths to obtain knowledge and materials to construct a chemical weapon an explosive device, but that agents "disrupted his evil intentions before he could cause harm", according to Kitv4 news.
Between December 2019 and March this year, Mr Sandiomire allegedly ordered materials online to make the "destructive device", while in February he allegedly purchased items from a hardware store that, when combined create, create toxic chlorine gas.
That same day, on 24 February, he allegedly searched for blueprints and floor plans of a building in Honolulu, which the FBI identified as only "Building A", which he visited two days later on 26 February.
According to security camera footage cited by the FBI in its indictment, Mr Sandomire allegedly slipped into the building through an open door and took pictures of the structural support columns inside a parking garage, below a recreational and pool area, as well as large air vents that serve a 16,000-foot space of the building.
He also allegedly asked for copies of floor plans form front desk staff, which they did not provide, while later taking photos of a physical model of the building from the developer's office.
An FBI search of his personal computer allegedly found a note titled "destroy [building A]" by using chemicals and explosives, as well as folders with research into chemical weapons, biological weapons, improvised munitions and explosive devices.
Other folders were labelled "my attack plan", "explosives", "building demolition", and "biowarfare", and contained about 54 books about related topics plus a document called Advanced Chemical Weapons Design and Manufacture: Chemicals that Kill in 30 Seconds or your Money Back.
US district attorney for Hawaii, Kenji M Price, this was the second case that involves a federal chemical weapons statute brought before his office this year.
"These kinds of cases underscore the importance of vigilant action by law enforcement to protect the public from the acquisition and use of materials that can cause devastating harm to our communities," Mr Price said.
According to reports in local news Khon2, the FBI arrested Mr Sandomire on Sunday for allegedly targeted a Queen's Medical Centre physician who had previously evaluated him after a past drug overdose.
Mr Sandomire, who is being held without bail in a federal detention centre, was also allegedly hospitalized in August and September last year after burning himself from throwing explosive powder onto a heat source.
If found guilty, he faces life imprisonment.