A Russian general has been arrested and placed in pre-trial detention on fraud charges, part of a sprawling investigation into the extortion of soldiers, the RBC news outlet reported Friday, citing sources familiar with the matter.

Major General Alexander Dembitsky headed a recently created army corps within the Leningrad Military District. Legally attached to his unit was Yastreb, a small private mercenary group.

It remains unclear when Dembitsky was discharged from the military. Russian investigators have not commented publicly on the case.

According to RBC, Yastreb’s founder, Alexei Marushchenko, testified against Dembitsky as part of a plea deal in a separate criminal probe.

Marushchenko faces multiple charges, including murder, weapons trafficking, large-scale fraud, extortion, kidnapping and abuse of power.