Ricin was found in the former martial arts studio of the man suspected of sending poison letters to President Barack Obama and other officials, and it was discovered on a dust mask and other items he threw in the trash, federal prosecutors said in a court document made public Tuesday.

The affidavit says an FBI surveillance team saw James Everett Dutschke remove several items from the studio in Mississippi on April 22 and dump them in a trash bin down the street. The items included a dust mask that later tested positive for ricin, the affidavit said.

Traces of ricin also were found in the studio, and Dutschke used the Internet to buy castor beans, from which the poison is derived, the affidavit said.

Dutschke, 41, was arrested Saturday as part of the investigation into poison-tainted letters sent to Obama, U.S. Sen. Roger Wicker and Judge Sadie Holland in Mississippi. He is being held without bond pending a hearing Thursday. He faces up to life in prison if convicted.

The FBI has not yet revealed details about how lethal the ricin was. A Senate official has said the ricin was not weaponized, meaning it wasn't in a form that could easily enter the body. If inhaled, ricin can cause respiratory failure, among other symptoms. No antidote exists.

Dutschke told The Associated Press last week that he didn't send the letters. His lawyer, George Lucas, had no comment Tuesday.

Attention turned to Dutschke after prosecutors dropped charges against an Elvis impersonator who says he had feuded with Dutschke in the past.

The affidavit said that on evening of Dec. 31, 2012, someone using Dutschke's computer “downloaded a publication, Standard Operating Procedure for Ricin, which describes safe handling and storage methods for ricin, and approximately two hours later, Immunochromotography Detection of Ricin in Environmental and Biological Samples, which describes a method for detecting ricin.”

The affidavit also said numerous documents found in Dutschke's home had “trashmarks” that were similar to ones on the letters sent to the officials. “Trashmarks are flaws or marks that come from dirt, scratches, or other marks on the printer. They are transferred to each piece of paper that is run through the printer,” it said.

A witness, who is not named in the document, told investigators that Dutschke once said years ago that he knows how to make poison that could be sent to elected officials and “whoever opened these envelopes containing the poison would die.”

Holland dismissed a civil suit that Dutschke filed in 2006 against the witness, who accused him of making sexual advances toward the witness' daughter, the affidavit said. In April, Dutschke pleaded not guilty in state court to two child molestation charges involving three girls younger than 16. He also was appealing a conviction on a different charge of indecent exposure. He told AP that his lawyer told him not to comment on those cases.

Dutschke's MySpace page has several pictures with him and Wicker. Republicans in Mississippi say Dutschke used to frequently show up at events and mingle with people, usually finding a way to get a photo of himself with the headliner.

The first suspect accused by the FBI, Paul Kevin Curtis, 45, was arrested on April 17, but the charges were dropped six days later. After his arrest, Curtis said he was framed and gave investigators Dutschke's name as someone who could have sent the letters, the affidavit said.

Curtis has said he knows Dutschke and they feuded over the years. (AP)