Traces of the poison ricin have been found on items and at a business that once belonged to Everett Dutschke, the Mississippi man arrested last week for mailing a toxin-laced letter to U.S. President Barack Obama.
An affidavit states Dutschke's computer was used to purchase castor beans - the precursor to ricin - online.
On April 22, investigators watching Everett Dutschke saw him dump objects in a garbage bin near his martial arts school. Among the items recovered were a mask, a coffee grinder and a box of latex gloves.
Forensic officers also took evidence from his taekwondo school and traces of the poison were found on the mask and samples taken from the school.
Documents from a printer owned by Dutschke also showed the same printing artifacts - unique to each printer - as were found on the toxic letter.
Dutschke made a short court appearance Monday, but said little other than confirming he understood the charges against him.