BRANDON, Miss. (AP) — The arrest of a 41-year-old Mississippi martial arts instructor in a case of poison-laced letters sent to President Barack Obama and others capped a week in which investigators initially zeroed in on a rival of James Everett Dutschke, then decided they had the wrong man.

Federal authorities arrested Dutschke early Saturday at his home in Tupelo. He was charged with “knowingly developing, producing, stockpiling, transferring, acquiring, retaining and possessing a biological agent, toxin and delivery system, for use as a weapon, to wit: ricin.”

U.S. attorney Felicia Adams and Daniel McMullen, the FBI agent in charge in Mississippi, made the announcement in a news release. Dutschke is expected to appear Monday in U.S. District Court in Oxford.

Authorities said the hunt for a suspect revealed tie after small-town tie between the two men being investigated and the 80-year-old county judge who, along with Obama and U.S. Sen. Roger Wicker of Mississippi, was among the targets of the letters.

Dutschke’s house, business and vehicles in Tupelo were searched earlier in the week, often by crews in hazardous materials suits. He also had come under surveillance.

Dutschke’s attorney, Lori Nail Basham, said she had no comment. Earlier this week, she said that Dutschke was cooperating fully with investigators and Dutschke has insisted he had nothing to do with the letters. He faces up to life in prison, if convicted.

He already had legal problems. Earlier this month, he 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 The Associated Press earlier this week that his lawyer told him not to comment on those cases.

The letters, which tests showed were tainted with ricin, were sent April 8 to Obama, Sen. Roger Wicker of Mississippi and a Mississippi judge, Sadie Holland.

Wicker spokesman Ryan Taylor said since the investigation was ongoing, the senator couldn’t comment.

Charges in the case had initially been filed against a 45-year-old Elvis impersonator, Paul Kevin Curtis, and then dropped.

Curtis was arrested on April 17 at his Corinth, Miss., home, but the charges were dropped six days later and Curtis, who says he was framed, was released from jail.

The focus then turned to Dutschke, who has ties to the former suspect, the judge and the senator. Earlier in the week, as investigators searched his primary residence in Tupelo, Dutschke told AP: “I don’t know how much more of this I can take.”

“I’m a patriotic American. I don’t have any grudges against anybody. … I did not send the letters,” Dutschke said.

Curtis’ attorney, Christi McCoy, said Saturday: “We are relieved but also saddened. This crime is nothing short of diabolical. I have seen a lot of meanness in the past two decades, but this stops me in my tracks.”

Some of the language in the letters was similar to posts on Curtis’ Facebook page and they were signed, “I am KC and I approve this message.” Curtis’ signoff online was often similar.

Dutschke and Curtis were acquainted. Curtis said they had talked about possibly publishing a book on a conspiracy that Curtis insists he has uncovered to sell body parts on a black market. But he said they later had a feud.

Curtis’ attorneys have said they believe their client was set up. An FBI agent testified that no evidence of ricin was found in searches of Curtis’ home. Curtis’ attorney, Hal Neilson, said the defense gave authorities a list of people who may have had a reason to hurt Curtis and Dutschke came up.

Judge Holland also is a common link between the two men, and both know Wicker.

Holland was the presiding judge in a 2004 case in which Curtis was accused of assaulting a Tupelo attorney a year earlier. Holland sentenced him to six months in the county jail. He served only part of the sentence, according to his brother.

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 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.

On Saturday, Steve Holland said he can’t say for certain that Dutschke is the person who sent the letter to his mother but added, “I feel confident the FBI knows what they are doing.”

“We’re ready for this long nightmare to be over,” Holland told AP.

Associated Press writer Jack Elliott Jr. in Jackson contributed to this report.