Here are some details about Viktor Bout, a Russian arms dealer serving a 25-year sentence in the U.S.

The U.S. agreed to release Bout in a high-level prisoner swap to win the release of WNBA star Brittney Griner on Thursday.

Bout is a former Soviet Army lieutenant colonel whom the Justice Department once described as one of the world’s most prolific arms dealers.

He was was serving a 25-year sentence on charges that he conspired to sell tens of millions of dollars in weapons that U.S officials said were to be used against Americans.

The Biden administration was ultimately willing to exchange Bout if it meant Griner’s freedom, The Associated Press reported.

His exploits inspired a 2005 Hollywood movie starring Nicolas Cage. He was also the subject of a documentary.

Bout once earned the nickname “the merchant of death.”

—Reporting by The Associated Press is included in this article.