[9][10] Karjel grew up in the small city of Örebro, the son of a Swedish mother, Solveig, and an Estonian father, Raivo.

"[11] In 1987, Karjel traveled to the Amazon jungle, where he lived with Swedish missionaries in a village dependent on the cocaine trade, material he used in his second book, Shadow of the River.

In 1993, he appeared in the Swedish TV version of Fort Boyard (game show), in which he had to arm-wrestle a muscleman, do complex math under pressure, and dive into the ocean to retrieve a key.

[13] In 2010, Karjel commanded a helicopter squadron on the ship HSwMS Carlskrona (P04), as part of the EU's Operation Atalanta fighting Somali pirates in the Gulf of Aden.

[16] From 2011 to 2013, he directed an $800 million program for the Swedish Air Force, procuring Black Hawk helicopters for medivac operations in Afghanistan.

[17] In 2013, he held a writer's residency at Ledig House, Omi International Arts Center, upstate New York.