The Islamabad High Court (IHC) on Tuesday said that white-collar crimes were not easy to trace, and the National Accountability Bureau (NAB) required custody of former president Asif Ali Zardari and his sister Faryal Talpur.The order stated that “no mala fide or ulterior motives” were found on NAB’s part “which is the core principle for grant or refusal of the bail before arrest”. Last week, the high court had dismissed the applications for a pre-arrest bail by Zardari and Talpur in the fake bank accounts reference. Following the dismissal, Zardari was arrested by a 15-member NAB team, while his sister, Talpur, was taken into custody on June 14. Both the PPP leaders are in NAB custody on remand.Justice Aamer Farooq and Justice Mohsin Akhtar Kayani, who announced the verdict, in their written order issued on Tuesday said that white-collar crimes were not easy to deduct and trace and could not be equated with other general offences. The accused persons were to be confronted with the documents and questioned about the same repeatedly in order to build up the chain, it said, adding that the NAB authorities required the custody of the petitioners for the same purpose.According to the order, the legal counsel for the petitioners had argued that since a reference had been filed, NAB Chairman Justice (r) Javed Iqbal had “no lawful authority” to execute arrest warrants. They had also said that as bonds had been furnished, the petitioners could not be arrested.