(CNN) -- After months of bomb threats at the University of Pittsburgh, an anonymous group that calls itself the Threateners has claimed responsibility for the most recent e-mail threats and announced to the school's student-run newspaper that it will stop sending them.
Michael Macagnone, whose term as editor-in-chief of The Pitt News ended Sunday, said the paper received an anonymous e-mail Friday claiming that the bomb threats plaguing the school since February 13 would end if university officials revoked a $50,000 reward for anyone who came forward with information that led to an arrest.
The paper received a second e-mail Saturday, after university officials revoked the reward, saying there would be no more threats, Macagnone said.
The university has received more than 140 threats since February, according to spokesman Robert Hill. The threats have not yielded any explosives, but the majority of them have resulted in evacuations of dorms, libraries and other campus buildings.
Hill confirmed that the university had withdrawn the reward but would not comment on why it did so.
The author of the anonymous e-mail to The Pitt News said that the Threateners began sending the bomb threats March 30 because the university issued a reward for "some young kid who'd pranked the university," Macagnone said. The group said it was not responsible for threats before that date and also said it was not affiliated with anyone who had been "publically identified as suspects."
Macagnone said he handed the first anonymous e-mail over to police Friday. The paper published a report on the e-mail Saturday, after a 24-hour period without any threats, which the anonymous author promised in the first e-mail.
"We started thinking the e-mail was a little bit more authentic when it accurately predicted that gap," Macagnone said.
Since the second e-mail promising an end to the threats, no more have been reported through the school's emergency alert system.
Despite the lull, university officials are restricting final exams, scheduled to start this week, to five campus buildings. All of them will be swept for explosives at the beginning of each exam day.
According to a letter posted on the university's website by Senior Vice Chancellor Patricia Beeson, any buildings that receive bomb threats will be checked for explosives but evacuated only if law enforcement officials deem it necessary.
"These arrangements reflect the expert advice we have received from law enforcement professionals, the experience we have gained over the past several weeks, and the special circumstances associated with finals week," the letter says.
The Justice Department said in a statement April 11 that investigators were making "significant progress." U.S. Attorney David J. Hickton said they were focused on "potential suspects."
Investigators have remained mum on any potential leads.
An FBI spokesman declined to comment on the investigation, and a Justice Department spokeswoman did not return calls for comment.
Katherine Anne McCloskey, 55, and Seamus Johnston, 22, of Cambria County, Pennsylvania, had been subpoenaed in connection with the investigation. The pair testified before a grand jury April 17, according to Johnston.
Johnston said FBI officials returned to the couple's apartment the following day and seized their computers, cell phones and other files.
"I feel very violated," said Johnston, who denies any connection to the bomb threats at Pitt.
Johnston, who is transgendered, is filing a lawsuit against the university alleging discriminatory treatment after being charged with trespass, indecent exposure and disorderly conduct after using the men's locker room for a weight-training class during his junior year, he said.
He said he has since been expelled.
"I feel that we're being investigated solely because I have a lawsuit pending against the university," Johnston said.
The FBI also seized a server from the New York headquarters of Internet service provider May First/People Link on Wednesday, according to a statement from the company.
The server was operated by the European Counter Network, a provider that runs an anonymous remailer service, allowing people to send e-mails completely anonymously, according to the statement released by May First/People Link Director Jamie McClelland.
McClelland added that the server was seized in accordance with a search warrant issued by the FBI the previous week requesting all of the information, including IP address, in connection to bomb threat e-mail messages relayed through their servers.