An Arizona man accused of threatening to blow up Philadelphia's Liberty Bell was charged Sunday, police said.
Carlos Balsas, 41, of Tempe, Arizona, is charged with terroristic threats, bomb threats and several other offenses, police spokeswoman Christine O'Brien said. Prosecutors approved the charges and will take up the case Monday, she said.
Arizona State University spokeswoman Julie Newberg said Balsas worked at ASU from 2004 to 2011.
According to ASU's website, Balsas was an Assistant Professor in the School of Planning which is part of the school's Global Institute of Sustainability.
Authorities say Balsas claimed to have explosives as he entered the historic site. Later, two black backpacks were found in front of the Liberty Wheels wheelchair and scooter rental shop in downtown Philadelphia.
Police said a bomb squad was called in and secured the scene but found that the bags did not contain explosives.
"I have no idea why" the man allegedly did this, O'Brien said.
The bell is considered an iconic monument to American independence.