Bomb threats to the University of Pittsburgh kept the campus on edge Wednesday night and Thursday morning despite an arrest of a possible suspect.
A rash of more than 50 threats have been made against the university and its officials since mid-February, causing constant disruptions to classes and activities on campus and evacuation of campus buildings and officials' homes.
On Wednesday afternoon, the Pittsburgh University police department and Allegheny County Police arrested Mark Lee Krangle, 65, of Hudson, N.Y., as he arrived at the Pittsburgh airport on a flight from New York on charges of harassment and terroristic threats.
Krangle allegedly sent threatening emails to four professors at the university, and wrote that he was coming to Pittsburgh to get his theories about the bomb threats out to the public, according to the Pittsburgh Tribune-Review. Krangle's Facebook profile shows extensive musings on the perpetrator and motive behind the bomb threats.
Hours after Krangle was arrested, however, the university received two more bomb threats. Around 10 p.m. on Wednesday evening, students were evacuated from a residence hall after a threat was emailed to ABC News' Pittsburgh affiliate, WTAE, saying "Tell Pitt cops - bombs are in the Litchfield Towers and in the William Pitt Union building on campus."
Around 5 a.m. today, five more residence halls were evacuated due to threats. The university said Wednesday the investigation into the threats is ongoing.
Pittsburgh University police were unavailable for comments this morning. The FBI and Pittsburgh police department are assisting in the investigation, according to a police department spokeswoman.
Criminal records show that Krangle was convicted in 2003 of threatening to kidnap, a felony offense for which he served prison time and was ordered to undergo psychiatric therapy. The court documents from the case are sealed.
On his Facebook page, Krangle claims he received his Ph.D. from Pitt, and offers a link to an e-book he authored about his role in the Jimmy Carter administration. He notes that the federal case against him in 2003 was caused by a letter he wrote to ABC TV, alleging that he had information about the 9/11 attacks before they happened.
Krangle, in his recent Facebook posts, tied the Pitt bomb threats to the Occupy Wall Street and Occupy Pittsburgh movement.
"I'm a former Pitt teaching fellow and doctoral candidate who became involved in the intelligence community since leaving. I believe more than one person is involved, directed by a mastermind. I believe the motive is revenge for a host of wrongs committed by Pittsburgh's one percent, though I have no information that the Occupy movement is responsible," Krangle wrote in one post.
A $50,000 reward has been offered by the university to anyone who can provide information leading to arrests in the case.
One recent threat was made late Tuesday night, targeting Chancellor Mark Nordenberg's house in Oakland, according to WTAE. The chancellor declined to evacuate or have the police dogs search his home.
Many professors and students at the university are planning an early exit for the end of the semester, telling ABC News that final exams have been canceled or made available online so students can complete them at home.
"I was evacuated at 4 o'clock in the morning last Monday, and it was honestly really terrifying," student Sarah Halperin told WTAE.