 Witnesses called by the State supported Farrar 's and the prosecutors ' earlier claims that police had been called to the home a month before the fire , that Green 's behavior had been cause for concern at the time , and that Farrar had turned in to police at that time seed packets containing castor beans . The Earl May store clerk who had identified Green as the purchaser of multiple packets of castor bean seeds testified to that effect . Medical evidence was presented that Farrar 's illness had not fit neatly within the parameters of any known disease , but that its presentation matched the symptoms of ricin poisoning . An FBI criminologist provided testimony that he had tested for ricin antibodies in Farrar 's blood approximately two months after Farrar 's last acute symptoms , and found antibodies there in such large amounts that he could confidently state that Farrar had been subjected to repeated exposures to ricin . 
