Barnard College and Columbia University said they have received a wave of “abhorrent and viciously racist” robocall messages related to the recent murder of freshman Barnard student Tessa Majors from a white-supremacist group.

The schools said Thursday in a statement that the calls were going to faculty and staff landlines at both institutions.

“We write to let you know that we are actively looking into this with the NYPD and are working to block the caller,” said the statement. “We take this attack on our values extremely seriously.”

New York Mayor Bill de Blasio tweeted about the calls, writing: “White supremacists are morally bankrupt, and these robocalls in the wake of an unspeakable tragedy are disgusting.”

“The Barnard and Columbia community rejects hate—and so does New York City,” he added.

Also on Thursday, police located and released a 14-year-old boy wanted for questioning in 18-year-old Majors’ fatal stabbing, which was the alleged result of a robbery gone wrong in Morningside Park on Dec. 11. Authorities said they thought the teen’s family may have been hiding him until a mark on his hand healed, The New York Times reported.

Police swabbed his cheek for DNA and questioned him for hours on Thursday before letting him go without charges, according to the New York Post.

Two other minors are also suspected of playing a role in the high-profile case. A 13-year-old suspect was arrested and charged on Dec. 12. He allegedly told detectives he watched two of his friends choke and stab Majors, according to CBS New York. A third teenager was also released without charges.

“Although he has since been released to the custody of his attorneys, the investigation remains very active,” NYPD Chief of Detectives Rodney Harrison wrote on Twitter. “Our detectives are the best at what they do and are committed to finding justice for all parties involved.”