Wilhelmus Adrianus Leijdekkers, the brother and alleged financial operator of one of Europe’s most wanted Dutch crime figures, Joseph Johannes “Bolle Jos” Leijdekkers, has been arrested by Turkish intelligence and Istanbul police.
The detention occurred on May 16, 2026, in Istanbul’s Pendik district, as part of a coordinated operation by national intelligence agents and narcotics officers, Turkish authorities said. The arrest was carried out in accordance with an Interpol Red Notice requesting his arrest on an international scale.
According to Turkish prosecutors, Wilhelmus Leijdekkers has long been regarded by investigators as a senior figure within a Dutch-based international drug cartel and the organisation’s so-called “black box.” While Joseph Leijdekkers is accused of directing large-scale cocaine shipments, his brother is accused of overseeing the criminal enterprise’s financial side, including managing proceeds, arranging transfers, and laundering illicit gains through real estate and luxury goods investments. Authorities estimate the amounts involved are in the billions of Turkish lira, though precise figures and tracing are still being worked out through forensic accounting and investigations.
The arrest comes after Turkish authorities increased their scrutiny of the Leijdekkers network. Previous operations in Istanbul, according to officials, targeted cartel associates and operatives, and intelligence revealed that one of the Leijdekkers brothers was using Turkey as a base to coordinate money-laundering activities on the ground. Turkish authorities are portraying the latest operation as a significant strike against the organisation’s financial infrastructure.
Following the arrest, Dutch authorities requested extradition immediately. Wilhelmus Leijdekkers is being held in Istanbul while legal proceedings regarding the Dutch extradition request are ongoing.
Extradition procedures can be complex, requiring both judicial review in Turkish courts and diplomatic coordination; Turkish authorities have stated that the necessary legal steps have been taken. Dutch officials have stated that they will pursue the case and expect close cooperation from Turkish prosecutors and law enforcement.
Wilhelmus Leijdekkers previously received international attention in 2024 when a Turkish court released him from custody despite an ongoing Dutch request for extradition on drug trafficking and money laundering charges. This release sparked criticism in the Netherlands, with concerns that he would remain at large and able to coordinate criminal finances.
Investigators in both countries said they hope the arrest of the alleged “black box” will yield documents, records, and leads that will help them locate Joseph “Bolle Jos” Leijdekkers, who is still at large. Authorities said they will continue to pursue asset tracing, forensic financial analysis, and international cooperation to dismantle the cartel and press charges as needed. Turkish officials described the operation as a significant international anti-organised crime operation.
