NISKAYUNA — It sounded like a real threat.

Three female high school students in Schenectady County, at odds with other students, suddenly received menacing emails. Around the same time last fall, videos appeared on YouTube that appeared to threaten students at the high school.

Some video footage was aimed at the police. Fear of possible school violence escalated. The FBI was even called in. Now, four-and-a-half months later, investigators say the mystery has been solved.

And it was not a real threat. It was a high school student from Canada trolling the Internet.

"It appears that based on all the facts that the threat wasn't clear and present," Detective Sgt. Dan McManus of the Niskayuna Police Department said Tuesday. Investigators discovered that the girl, whose name was not released, sent the threats to two female students in Niskayuna High School and a third in Schenectady High School. She had no connection to any of the girls; rather, she met them through an Internet chat forum, McManus said.

There, he explained, the girl began to "follow" a student and learned she and other girls in the forum were involved in some sort of fight. In turn, she created videos for the purpose of keeping the fight alive.

The depth of information she had at her disposal, McManus explained, led police to initially believe the culprit was local.

In a statement, Niskayuna police said: "Based on their online posts, the suspect had been able to collect enough personal information on the youths to make the videos appear to be made by someone they knew."

The case triggered outrage in Niskayuna and became a topic at school board meetings where worried parents shared concerns that students could be hurt.

The investigation led police eventually to Ontario, Canada, where the girl's case will be handled, McManus said. In New York, the crime would have been an A misdemeanor, punishable by at most a year in jail.

At the time of the threats, Niskayuna's school principal, John Rickert, sent an email to parents informing them about the harassment. He later assured the parents, after a second video was released, that "the FBI is also aware of this and is actively investigating the source of the videos. Subpoenas have been issued for the IP addresses and, once granted, law enforcement will move forward with closing the case."

He also said "This latest video, like the others, does not reference any threats toward the school or shootings at school."

At the time, the principal reminded parents that the district has policies on Internet use. He urged them to speak with their children about the consequences of violating the rules.

On Tuesday, district Duperintendent Susan Kay Salvaggio echoed that theme. "We are pleased that this issue has been brought to a close, and are grateful for the work and partnership of law enforcement every step of the way on behalf of the safety of our students, staff, and community," Salvaggio wrote in a letter to parents on the district website. "Even as we learn that these videos were not produced locally, this case continues to be a reminder for parents, students and our schools, of the world we live in as it relates to teens and technology."

rgavin@timesunion.com • 518-434-2403 • @RobertGavinTU