- "Austrian-born, fled to Germany to evade murder charges. Served with KSK under false ID until mission gone-wrong. Civilians died. Identity discovered, escaped custody before court martial. Maintains innocence."
- — In-game biography
Sebastian Krueger was born on March 29, 1985. He joined the Bundeswehr under the identity of "Josef Doss". Kreuger received exceptional marks in Long Range Surveillance training and passed subsequent selection process for the Kommando Spezialkräfte.
After three years, he was inducted into the KSK 4th Platoon under Lieutenant Hans "Golem" Blaustein. Blaustein befriended Krueger in effort to integrate him with the rest of the squad as he claimed to see "talent in a troubled mind".
On April 12th, 2018, during Operation Nachtigall in Mozambique, civilians were found killed with 7.62 NATO rounds consistent with Krueger's weapon. Krueger escaped KSK custody two days later. It is suspected "Golem" aided or interfered with the escape of Krueger but evidence was inconclusive. Krueger's friendship with Blaustein ended after his removal from the KSK.
Krueger fled to Eastern Europe where he made contact with Chimera and entered a long-term contract with currently 2 years in active service.
In March 2020, Al-Qatala's new leader Khaled Al-Asad launched a full-scale assault against Verdansk in Kastovia. Operators from Coalition and Allegiance were deployed to Verdansk to stop Al-Qatala as part of the Armistice initiative.
- Krueger's name is spelled differently in-game and in other media. His name appears as "Kreuger" in the Operator menu while he is named "Kruegar" in the Making Call of Duty: Modern Warfare artbook.
- Krueger's appearance is based off the Danish Frogman Corps gear.
- Krueger's blood type is AB+
- Krueger is ambidextrous with a right eye dominant and a visual acuity of 21/20.
- Though Krueger's dossier states that his hair is dark blonde, his in-game model has dark brown hair.
- In the game mode Infected, the 'Infected' will always be Krueger with the Shrouded skin.
- Also, an 'Infected' player will use whatever Finishing Move they have equipped for Krueger.