Federal prosecutors filed documents Tuesday stating that ricin was found on items discarded by the Mississippi man charged with sending a letter to President Obama that was laced with the deadly poison.

According to the FBI affidavit, James Everett Dutschke removed several items from his former martial arts studio in Tupelo, Miss. -- including a dust mask found in a nearby trash can.

The items tested positive for ricin, and trace amounts of the poison were found inside the studio. The 41-year-old Dutschke also made two eBay purchases in late 2012 for a total of 100 red castor beans, which can be used to make ricin, according to the documents.

The release of the documents marks the latest development in the unusual case in which Dutschke purportedly had been engaged in an ongoing feud with Elvis impersonator and fellow Mississippi resident Paul Kevin Curtis, who initially was arrested but later cleared of all charges in the case.

U.S. marshals took Dutschke into custody Saturday at his home, after dropping charges Tuesday against Curtis.

Dutschke, in addition to his interaction with Curtis, is said to have ties to Republican Mississippi Sen. Roger Wicker and local Judge Sadie Holland, to whom ricin-laced letters also were sent. Dutschke is also charged in connection with the sending of all three letters, which included the sentence: “I am KC and I approve this message.”

The eight-page document states Dutschke told the property manager at his former business -- Tupelo Taekwondo Plus -- he needed to recover a left-behind fire extinguisher, mop and bucket. Then an FBI surveillance team observed him on April 22 enter the premises, remove items and put them into a red, 1993 Mercury Villager-Sport Van.

Dutschke then drove about 100 yards and was observed putting the items into the trash can. Federal officials then recovered from the receptacle the mask, a box for a Black and Decker Smart Grind coffee grinder and a box containing latex gloves.

“I know that a coffee bean grinder could be utilized in the process of extracting ricin from castor beans,” an investigator explained in the documents.

The letters addressed to Obama and Wicker were intercepted April 16 at a Washington-area mail-screening facility. Investigators learned April 17 that the letter to Holland has arrived about a week earlier, according to the documents.

In 2004, Holland sentenced Curtis to six months in jail in connection with the assaulting a Tupelo attorney.

And Holland's family has had political skirmishes with Dutschke.Her son, Steve Holland, a Democratic state representative, said he thinks his mother's only other encounter with Dutschke was at a 2007 political rally when Dutschke ran against him as a Republican.

Holland said his mother confronted Dutschke after he made a derogatory speech about the Holland family. She demanded that he apologize, which Holland says he did.

The Associated Press and Fox News' John Roberts and Mike Levine contributed to this story.