Krueger enlisted in the Bundeswehr under false documents in the name of "Josef Doss". It is now known that this was his way of hiding from a murder charge in Salzburg, Austria (not convicted). Received top marks in the long-range intelligence training program and was selected to serve in the KSK special unit. After 3 years, he enlisted in KSK 4th Platoon.

He served in KSK 4th Platoon under the command of Hans Rudolf Blaustein (call sign "Golem").

On April 12, 2018, during an operation in Mozambique, it was discovered that civilians had been killed by 7.62 rounds compatible with Kruger's weapon. Kruger escaped from KSK custody two days later. It is suspected that "Golem" aided or hindered Kruger's escape. Krueger's friendship with Blaustein ended after he left KSK.

Krueger fled to Eastern Europe where he made contact with Chimera and signed a long term contract with 2 years of active service.

In March 2020, al-Qatala's new leader, Khaled al-Asad, launched a full-scale offensive on Verdansk in Qastawiya. As part of the Truce Initiative, Coalition and Special Forces operators were deployed to Verdansk to stop al-Qatala.