Northwestern University is mourning the death of alumnus James Foley, a 40-year-old journalist killed by Islamist extremist militants.
Video released Tuesday shows a member of ISIS beheading Foley and threatening another journalist's life if the United States does not stop the airstrikes it has carried out against the group since Aug. 8.
Foley graduated from Northwestern's Medill School of Journalism in 2008.
His former professor, Stephan Garnett, says Foley was aware of the dangers of his chosen lifestyle.
"He knew the risks he was taking. He was willing to take them," Garnett said.
"Jim actually went to the places and to the people that most of us avoid."
Foley was taken captive almost two years ago in Syria. Before that, he spent 44 days in a Libyan jail, and in 2011 he spoke to Northwestern journalism students about reporting from conflict zones and how to protect yourself.
"It's not worth your life, no matter what romantic ideal you have, no matter what ethic you think you have, it's never worth it," Foley told the students.
U.S. officials told NBC News Wednesday that the Pentagon attempted a rescue operation to free Foley and other U.S. hostages held in Syria by Islamist militants earlier this summer, but the mission failed because the hostages weren't where U.S. planners thought they were.
"I can't imagine what was going through his mind all those months, almost two years that he was held in captivity," Garnett said.