PITTSBURGH (AP) — A founding member of a Scottish terror group was indicted on charges he emailed 17 bomb threats to the University of Pittsburgh earlier this year, disrupting campus life and forcing the evacuation of more than 100 buildings.

Adam Stuart Busby, 64, of Dublin, Ireland, was charged Wednesday with the emailed threats sent to the school between April 6 and 21, and also with emailed bomb threats against federal courthouses in Pittsburgh, Erie and Johnstown in June. He's also charged with threatening Pittsburgh-based U.S. Attorney David Hickton — who led the investigation that resulted in Busby's indictment — in a June 20 email.

Busby is in custody in Ireland, but it wasn't clear when he'd be brought to Pittsburgh to face the new charges.

He has no known ties to Pittsburgh or the university, and Hickton wouldn't comment on why Busby allegedly sent the threats or whether they're related to his activities with the Scottish National Liberation Army, an outlawed militant group that seeks Scottish independence from the United Kingdom.

Prosecutors also announced new charges against two Ohio men, including one previously charged in June, for some YouTube threats that claimed university computers had been hacked. Those threats are not directly related to the bomb scares, but were uncovered as a result of the same investigation.

Busby is a prolific hoaxer. In 2010, an Irish court convicted him for sending a series of emails claiming that there were explosives devices on flights between London's Heathrow Airport and New York City. He was sentenced to four years in prison but was released early this year and allegedly sent the Pitt threats before he was returned to prison last month.

Busby is now charged with threatening to poison some English water supplies and then-Prime Minister Gordon Brown in 2010, along with some bomb hoaxes he allegedly called in to hotels and the media. He suffers from multiple sclerosis and appeared in a wheelchair before the High Court in Dublin last month.

The university began receiving bomb threats written on bathroom stalls in mid-February, for which nobody has yet been charged. Investigators don't believe those threats are tied to Busby, who allegedly sent his emails to capitalize on the momentum from the earlier threats.

The university was eventually the target of more than 40 emailed threats — some sent to the school, and others to local journalists who alerted authorities — all of which are attributed to Busby, though he's charged with sending only 17 of them. Hickton said the investigation involved complex efforts to trace the emails through overseas computer servers. Typically, federal authorities in wire fraud cases file charges for only a representative sampling of counts for which they have the most evidence.

In all, the university received 52 threats against 160 buildings that prompted 136 evacuations, Pitt Chancellor Mark Nordenberg said Wednesday.

Some emailed threats claimed to be sent by a group calling itself The Threateners — now identified as Busby — who expressed anger that the university issued a $50,000 reward for what the email suggested were harmless pranks. Busby, as The Threateners, allegedly emailed the student newspaper, The Pitt News, promising to stop if the university withdrew the reward. The university complied on April 21, although school officials didn't explain then why the reward was being withdrawn.

Busby faces 17 counts of wire fraud, each carrying up to 20 years in prison, 16 counts of sending false information or hoaxes each carrying up to 10 years, and two counts of international extortion, which carry up to two years each. The April 21 reward ultimatum wasn't deemed a hoax because the threats stopped after the university withdrew the reward.

The extortion counts relate to the ultimatum and a similar April 10 email that the university disregarded as unreliable because it contained misspellings and factual errors, Nordenberg said.

The threats cost the school more than $300,000 in direct expenses, including overtime for police and other staff, bomb squads and special equipment to detect such devices. That doesn't include time lost by faculty and students, who were evacuated from dorms at all hours.

Busby is the only person so far to be charged in connection with the bomb threats, though federal authorities charged an Ohio man in June with the YouTube video.

That man, Alexander Wakeland, 24, of Loveland, Ohio, was charged again Wednesday along with Brett Hudson, 26, of Hillsboro, Ohio, with conspiracy to target Pitt with Internet threats for the video and related emails and tweets from April 25 through May 23.

The men, allegedly claiming to be part of the hacking group Anonymous, threatened to release the computer files unless Nordenberg publicly apologized for not safeguarding students from the bomb threats. Pitt officials determined the computer information was never hacked.

The men declined to comment when reached by the AP.

Hickton said Wakeland and Hudson will turn themselves in next week to be arraigned on the charge, which carries up to five years in prison.