By Steve Tawa

PHILADELPHIA (CBS) — A former Arizona State University professor who was visiting Philadelphia has been ordered to stand trial on charges that include making a bomb threat inside the Liberty Bell Center earlier this year.

Today, 41-year-old Carlos Balsas was ordered to stand trial on charges stemming from the January 26th incident.

A security screener testified today that Balsas entered the Liberty Bell Center, on Independence Mall, with a messenger bag and backpack.  The screener says he was about to check them but Balsas refused to hand over the backpack, saying, “There’s explosives in there.”

The screener testified that he called for an armed security guard, and as Balsas walked out in a huff muttered, “This is how you treat people in America?”

Balsas is a citizen of Portugal.

National Park Service rangers arrested him nearby, at 7th and Market Streets.

“I couldn’t even venture a guess into what he was thinking,” said Philadelphia assistant district attorney Rob Frantz today, following the proceeding.

Frantz says bomb squad officers closed off the area, inspected the bags, and no explosives were found.

“They’ve got no other option at that point in time,” Frantz says.  “There’s a man running around the Independence Mall area, possibly with a bomb.  They can’t take a chance it’s not real.”

Balsas remains jailed on $250,000 cash bail.