Really I don't see any news in this, and the whole story sounds unserious to me, or is it that the details of the whole scenario are not given in this news, how can the police store seized assets in third-party custody, since the names of those arrested where not mentioned in the news, I guess the two people arrested includes the police men involved.
Perhaps what happened occurred during a raid, and he was arrested in connection with another case. Bitcoin was discovered during the investigation. The police officers may not believe they can track them, or it could be part of a corrupt system. Ironically, they claim Bitcoin is used for money laundering, and that its high transparency could reduce government corruption.