I do wish people would read posts properly before shooting their mouths off. Some of the comments on this thread are not at all helpful, and are pretty pointless.
The way I have read this, the present incident (arrest in Feb. 08) is entirely unconnected with the alleged incident in school in Nov. 06, except that the same police officer may have been involved in both (this is not clear to me from your posts). In any case, the same police force is involved and their actions in the Nov. 06 issue were the subject of an enquiry after the hearing.
You now have an issue because the police have been checking on your son far more frequently than on any of the other 6.
If the above is an accurate summary then it seems to me that, unless they have some good reason to do so (for example, your son is believed to be the instigator or ringleader of the alleged offence) this can reasonably be the subject of a formal complaint to the police force. You can look up on the internet how to go about making such complaints, which can eventually end up with the Independent Police Complaints Commission, if not resolved at an earlier stage.