Where is Don Foster's linguistics report?

According to Steve Thomas's book, Don Foster created an extensive linguistic report/presentation on the ransom note, concluding Patsy Ramsey was the most likely author.

Did Foster ever write up an official report? Or was his presentation just that - a presentation? If he did write up a report, where is it? In ST's book, we get a decent (and frankly, disappointingly brief) summary on what Foster presented. It's always left me really wanting to know/read more. Foster was a very highly skilled linguistics analyst/expert; that report, if it exists, could contain some incredibly valuable information.

Does anybody know more about this? Are there any FOIA records on it?