A bomb threat sent to campus printers in May was determined not to be credible. It is one of several offensive messages to pop out of printers and fax machines at Cal recently.

Over Memorial Day weekend, threatening fliers popped out of printers and fax machines on UC Berkeley’s campus, the most recent of several cases of disturbing documents emerging from campus machines over the past two years. A UCPD and FBI investigation determined that the threats were not serious, according to an email sent to the campus community earlier this week.

The flier, shared with Berkeleyside by a graduate student in the chemistry department, said explosives had been planted in campus buildings. The sender threatened to “blow up this whole block” if $25,000 was not wired to their account.

“If you try to contact the police, I’ll know. I also have access to your computers and email addresses,” the flier said.

The graduate student said he and others in his department stayed home the day the document appeared.

UCPD Lieutenant Marc DeCoulode declined to comment on the specifics of the threat because the investigation is ongoing, but said the department had contacted the FBI, as it does anytime an incident could be related to terrorism. The agency said the threat should not be taken seriously.

“While the recent messages may be stressful and disturbing to those who are receiving these fliers, it is important to note that UCPD and the FBI reviewed the messages that were reported and the FBI determined they were not credible threats,” said the campus-wide email from Larry Conrad, associate vice chancellor for IT and CIO.

But the threatening fliers are not the only concerning messages to have come out of campus printers and fax machines recently. Racist, anti-Semitic and homophobic fliers — some including Swastikas and white power messages — have also been discovered in machines around campus. Fliers found in January said, “It’s almost here, we take power on the 20th,” meaning the day President Donald Trump was inaugurated.

Neo-Nazi hacker Andrew Auernheimer, who goes by the name weev online, took credit for a batch of anti-Semitic and racist fliers sent to UC Berkeley and several other universities last spring. He told the Washington Post he had performed “mass printer trolling,” accessing thousands of printers through publicly available internet addresses.

UC Berkeley officials said they believe most, or all, of the disturbing fliers have come from remote users taking advantage of open-source access to Cal printers and fax machines.

Subscribe to the Daily Briefing Don’t miss a story. Get Berkeleyside headlines delivered to your inbox. Don’t miss a story. Get Berkeleyside headlines delivered to your inbox.

“We have efforts underway to remove printers from the open internet and better restrict access,” said Rita Rosenthal, spokeswoman for the UC Berkeley information technology office, in an email to Berkeleyside. “Technically the required changes are straightforward, but implementing them in a large, distributed organization is logistically challenging and will take time. Budgetary pressures have left us with fewer IT resources to carry out the work.”

Rosenthal said other security efforts are in the works, but the university has to strike a balance between preserving access to the network and preventing security risks.

In the meantime, at least one site on campus has taken its printers offline to avoid receiving additional unwanted material. The manager of a lab in the department of environmental science, policy, and management said she was startled to arrive at her desk one morning in early 2016 to find a three-page flier that had been recovered from one of the printers. It contained “really strange rhetoric” blasting Jewish, mixed-race and gay people, said the lab manager, who asked to remain anonymous because she has been harassed online in the past.

She made the decision to get rid of the internet connection on the lab’s printers. Now anyone who wants to print something must plug their computer into a printer.

“Given that the alternative is upsetting things coming out of the printer that are hurtful, no one’s complaining about walking down the hallway,” the lab manager said.

She said she wishes the UC Berkeley administration would respond to the offensive fliers and security concerns more aggressively.

“Hate speech can make people feel unsafe. These students don’t have the power to do anything,” she said.

DeCoulode said UCPD is working on preventing future incidents.

“We’re talking with our IT folks about the proper protocols. It is something we’re taking seriously and something we’re looking into,” he said.

When the fliers do appear on campus, they do not usually stick around for long.

“We were like, ‘We should burn these in a Bunsen burner,'” said the lab manager.