CAMBRIDGE — An anonymous tipster who reported threats of violence in local schools could be the same person who generated them, Cambridge Police Commissioner Robert C. Haas said Sunday at a public meeting.
Haas told a room packed with parents, grandparents, and school principals that, “in all likelihood, the person that originally authored the threats and the ‘good Samaritan’ are one and the same person.”
Police and schools officials have heightened security across the system after three messages last week — and another in mid-November — threatening attacks on middle schools.
Kieran Ramsey, an assistant special agent in charge at Boston’s FBI office, said investigators believe the threats are all coming from the same person.
It has been difficult to discern their origin with certainty, however, because the sender is using online tools to obscure his or her identity.
“Increasing use of encryption technology makes it very hard to trace back,” Ramsey said. He said he believes the threats have been sent along using Tor, a “dark web” software that enables online users to operate with anonymity.
“The anonymizing software makes it very, very challenging, if not in some cases impossible,” he said.
Cambridge police have decided to no longer engage with the sender, Haas said. He added that the language of the e-mails “was written in a way that made it seem like it was written by an adolescent,” but that it could have come from anybody.
The first threat came the Monday after the Nov. 13 Paris attacks that left at least 129 people dead and more than 350 wounded.
The initial threat was forwarded to Cambridge police through an anonymous tip line. The message said a bomb would be placed in “cambridge mass” schools that started with the letter “P,” said Haas.
Last week, the anonymous tipster was in contact with Cambridge police again, alerting them to threats with more specific language that described gun violence at specific schools, Haas and Ramsey said.
The e-mails were sent to city officials on Tuesday, Wednesday, and Friday, spurring an increase in security at five schools within three buildings, including the Amigos School, Putnam Avenue Upper School, the Vassal Lane Upper School, the Tobin Montessori, and the Kennedy-Longfellow schools.
Police will be present again at all schools in Cambridge on Monday, Haas said.
The meeting was organized by the Cambridge Community Response Network, a group that “helps residents, students, and workers identify the various tools and resources needed to build resiliency and better recover from a traumatic episode,” according to its website.
The network includes officials from Cambridge public schools, Cambridge’s public health department, and the city’s police force.
“I’m really gratified that with two days’ notice . . . people came out on their Sunday to be part of this, to find out more, and to help make sure that all of our children, all of our families, all of our teachers feel safe and secure,” said Brian Corr, director of the Cambridge Peace Commission, which is also part of the network.
In a question-and-answer portion of the meeting, parents raised concerns over how students might use the dark web, the safety of school buses, and the possibility of threats to the MLK School, which is under construction.
Attendance was down last week, Cambridge schools Superintendent Jeffrey Young said, although he did not have the exact numbers.
Charles Wade, of Cambridge, a father of two high school students and one middle-schooler, thought the meeting was helpful for the parents. He wants to know how schools officials plan to talk to students about the threats.
“They need someone to talk to the kids,” he said. “They’re very worried about their safety, and as well as who’s talking to them.”
Larry Berkowitz from the Riverside Trauma Center offered a few pieces of advice for parents, instructing them to tell kids to speak up if they see anything suspicious and to trust adults.
“Our children are going to continually take cues from us,” he said. “It’s really incumbent upon us to master our own fears,” he said.
“And let’s not keep the TV on 24/7,” he added. “It’s making sure they’re not getting too many scary messages,” he said.
Correction: An earlier version of this story incorrectly identified the Cambridge school superintendent, Jeffrey Young.