After what was called a “personal dispute” by authorities, a graduate student at the University of Southern California stabbed and killed psychology professor and mentor, Bosco Tjan.

David Jonathan Brown, who is now being held on $1 million bail, is a 28-year-old brain and cognitive science student who worked in a lab directed by Tjan.

“This was not a random act of violence,” said USC’s Department of Public Safety in a news release, cited by the Washington Post. The Los Angeles police were quick to ensure students that the incident was believed to be about a “personal dispute” and that the public were not in any danger. The incident happened just days after an attack, believed to be terrorism-related, injured 11 people on Ohio State University’s campus.

Tjan is survived by a wife and son.

To read the full report by the Washington Post, click here.

Letter from University President C.L. Max Nikias to the USC community regarding the death of Professor Bosco Tjan pic.twitter.com/tYzKKYZhPg

— Andrew Blankstein (@anblanx) December 3, 2016