There are quite a few ways that this sort of software could be on the drive without malicious intent by the police department. This article is pretty light on details but it doesn't sound like anyone has actually examined these drives to determine this.
Some possibilities:
* if the police computer was itself infected and the malware was trying to propagate
* The data was copied from a drive or computer that was infected
Some possibilities:
* if the police computer was itself infected and the malware was trying to propagate
* The data was copied from a drive or computer that was infected