I've been watching this one and even though the guy has some obvious issues the probable cause documents were pretty shallow. Because of the toxicity of ricin, testing can zero down to a very few parts per million. If he produced it in a home lab somewhere there would be traces, on his clothes, shoes, etc...So they are back to square one in the investigation.
*sigh* For all the people crying "government take over!" last week after the marathon bombings, there has been scant acknowledgment of this case, where a lack of evidence resulted in an innocent guy being exonerated. When the system works properly, nobody pays attention. Thanks for covering this.
THIS!