After a months-long investigation, FBI officials say they have identified a juvenile allegedly responsible for a string of racist bomb threats against historically black colleges and universities earlier this year, The Washington Post reports.

A senior FBI official told reporters that the suspect sent racially motivated threats to 50 institutions across the country in January and February. Investigators found no evidence of shooters or bombs on the campuses, but the events unnerved the HBCU community. The minor allegedly sent messages to the schools saying that active shooters and bombs were on campus.

Investigators initially believed a group of minors were responsible for the threats but ultimately linked the acts to one person. Officials say the minor is under government surveillance and restrictions but did not reveal any further details about the suspect due to their age. 

In February, several HBCUs were assailed with threatening calls, leading to campus shutdowns and sweeps. In response, the Biden administration announced plans to investigate the threats to HBCUs as a hate crime, per the Post. It offered HBCUs affected by bomb threats up to $150,000 in Education Department grants to upgrade security and provide mental health support. 

The FBI said agents are still investigating two other incidences of threats toward several HBCUs and other institutions in the country. Separately, the agency is looking into similar messages sent to 250 schools, but those messages do not appear to be racially motivated.