(N.Y. TIMES) Dozens of bomb threats at the University of Pittsburgh since mid-February have disrupted classes and dormitory life and prompted some students to find housing off campus just weeks before the semester ends.

Since the first warning about a hidden explosive device was found scrawled on the wall of a public women’s bathroom on Feb. 13, there have been 56 more — some written on walls, and some sent by anonymous e-mail to Pittsburgh news outlets. On Monday alone, 12 threats were received, a university spokesman said.

The police have said that there have been no explosions, and that no explosives have been found. The F.B.I.’s Joint Terrorism Task Force has joined the campus police in investigating the source of the threats, but no suspect has been named.

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