Steven Sotloff

U.S. journalist Steven Sotloff is pictured in this undated handout photo.  The Islamic State of Iraq and Syria (ISIS) released a video on Sept. 2, 2014 purporting to show the beheading of Sotloff, who went missing in Syria in 2013.

Steven Sotloff

American journalist Steven Sotloff, center, with black helmet, talks to Libyan rebels on the Al Dafniya front line, 25 kilometers west of Misrata, Libya, June 2, 2011. Sotloff was kidnapped in August 2013 near Aleppo, Syria.

Steven Sotloff

American journalist Steven Sotloff  takes notes while talking to Libyan rebels on the Al Dafniya front line, 25 kilometers west of Misrata, Libya, on June 2, 2011.

Steven Sotloff

Shirley Sotloff, who lives in Florida, appeals to the captors of her son, freelance journalist Steven Sotloff, 31, who was last seen in Syria in August, 2013 in a video released Aug. 27, 2014.

Steven Sotloff

White House press secretary Josh Earnest goes over his notes at the White House in Washington, Sept. 2, 2014. Earnest said after the release of the video that apparently showed the execution of Steven Sotloff: "This is something that the administration has obviously been watching very carefully. Our thoughts and prayers first and foremost are with Mr. Sotloff and Mr. Sotloff's family and those who worked with him."

Steven Sotloff

Steven Spotloff poses for an image published in the Kimball Union Academy yearbook. Sotloff graduated from the Meriden, N.H. boarding school in 2002.