Elon Musk’s well-documented drug use made him an easy target for Russian secret service agents, former FBI agent Johnathan Buma told German television broadcaster ZDF during a recently aired documentary.

Buma said there was evidence that both he and fellow billionaire Peter Thiel were targeted by Russian operatives.

“Musk’s susceptibility to promiscuous women and drug use, in particular ketamine, and his gravitation towards club life… would have been seen by Russian intelligence service as an entry point for an operative to be sent in after studying their psychological profile and find a way to bump into them, and quickly brought in to their inner circle,” Buma told ZDF.

“I’m not allowed to discuss the details of exactly how we obtained this information,” he added. “But there’s a vast amount of evidence to support this fact.”

Buma was arrested shortly after his interview with ZDF in March. His passport was confiscated and was temporarily released on bail.