Left on the phone of a Polish woman in 2022, it was from her older brother, Sylwester Suszek, the founder of Eastern and Central Europe’s biggest cryptocurrency exchange. He had disappeared two weeks earlier from the fuel depot in southwest Poland where he kept his helicopter.
“If you don’t help me, we will never see each other again,” he said, begging his sister to send Bitcoins to secure his release. Mr. Suszek has not been heard from since, and his family believes he was probably killed.
That largely forgotten mystery has now surged back to life. In April, the Polish lawyer who replaced Mr. Susczek at the helm of the exchange, Zondacrypto, also vanished.
“One crypto boss disappearing is bad enough, but two in four years is crazy bad,” said Robert Nogacki, a lawyer in Warsaw who represents Zondacrypto customers locked out of their accounts. “Nothing about this company makes any sense.”