I want to know the answer to the following question:
When did Sheptycki write about police cooperation?
All the background I'm provided with is that "By 1992, with the signing of the Schengen Treaty, which formalized aspects of police information exchange across the territory of the European Union, there were worries that much, if not all, of this intelligence sharing was opaque, raising questions about the efficacy of the accountability mechanisms governing police information sharing in Europe (Joubert and Bevers, 1996).". Is that enough to answer the question?
Answer: no