When poison-laced letters were sent to President Barack Obama and two other officials, it didn’t take long to track down a suspect based on a phrase often used by an Elvis impersonator named Kevin Curtis: “I am KC and I approve this message.”

Curtis was soon arrested at his house in north Mississippi and charged in the case. He swore he didn’t do it, and told investigators that maybe a longtime foe, a martial arts instructor named James Everett Dutschke, might have something to do with the case.

By the time Curtis was released on April 23, the FBI was already watching Dutschke.

It was another twist in a plot Curtis’ lawyer has called “diabolical.”

According to an FBI affidavit made public Tuesday, agents saw Dutschke the day before Curtis’ release hauling items out of his former martial arts studio in Tupelo, Miss.

Tests in the studio and on some of those items, including a dust mask, have tested positive for ricin, the same deadly substance found in the letters sent to Obama, U.S. Roger Wicker and Lee County, Miss., Judge Sadie Holland, the affidavit says.

The affidavit also said numerous documents found in Dutschke’s home had printer markings that were similar to ones on the letters and that he had used the Internet to buy castor beans, from which ricin is derived.

Dutschke, 41, was arrested Saturday by FBI agents at his home in Tupelo, and is being held without bond pending a preliminary and detention hearing Thursday in U.S. District Court in Oxford, Miss.

Dutschke told The Associated Press last week that he didn’t send the letters. His lawyer, federal public defender George Lucas, had no comment Tuesday about the information in the affidavit.

Annette Dobbs, who owns the small shopping center where the studio was located, said authorities padlocked the door to it last week. They also searched his house and vehicles.

Dobbs said Tuesday that FBI agents haven’t told her anything, including whether the building poses a health threat. Inside the studio is one large room with a smaller reception area and a concrete floor. Police tape covered the front and the small back door.

FBI spokeswoman Deborah Madden said Tuesday that the business, Tupelo Taekwondo Plus, was sealed off after evidence that was collected tested positive for “trace levels of ricin.”

“The FBI is now conducting further forensic examination for the purpose of identifying trace evidence, residues and signatures of production that could provide evidence to support the investigation,” she said in a news release.

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.

An expert at the National Bioforensics Analysis Center in Fort Detrick, Md., said the extraction process employed in this case appears to have been more involved than “merely grinding castor beans,” the affidavit said.

The most notable case of ricin poisoning was in 1978, when a Bulgarian dissident was lethally injected with it by an operative of that country’s secret service.

Dutschke bought 50 castor beans off eBay in November 2012 and 50 more in December 2012, the affidavit said.

The affidavit had been sealed since it was filed Friday in U.S. District Court in Oxford. It also said that on the evening of Dec. 31, 2012, someone using his “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.”

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.”

Judge Holland dismissed a civil suit Dutschke filed in 2006 against the witness, who accused him of making sexual advances toward the witness’s 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.

The lawsuit isn’t Dutschke’s only connection to Holland. She is part of a family that has had political skirmishes with him.

Her son, Steve Holland, a Democratic state representative, said his mother encountered Dutschke at a rally in the town of Verona in 2007, when Dutschke ran as a Republican against Steve Holland.

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.

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

The first suspect accused by the FBI, Curtis, also had also had ties to Holland. Curtis was arrested on April 17 at his Corinth, Miss., home, 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, but he wasn’t sure what caused it.

Dutschke made a brief appearance Monday in federal court, wearing an orange jumpsuit with his hands shackled. He said little during the hearing other than answering affirmatively to the judge’s questions about whether he understood the charges against him. U.S. Magistrate S. Allan Alexander set his preliminary and detention hearing for Thursday.

He faces up to life in prison if convicted.

(AP)