CHAPTER 2. SURRENDER OF PERSONS TO THE ICC
ยง 5. Decision on the request and actual surrender
Section 35
1. Notwithstanding section 33, subsection 1, and section 34, the decision on the time and place of surrender shall be deferred if and in so far as the person claimed is the subject of criminal proceedings in the Netherlands or all or part of a sentence imposed on him by a Dutch court is still eligible for enforcement.
Postponement - ongoing investigation or prosecution
EDIT.