TEXARKANA, Texas — A Flowery Branch native accused of sending ricin-laced letters to President Barack Obama and New York Mayor Michael Bloomberg is competent to stand trial, a federal judge said Wednesday.

During a brief hearing in Texarkana, Texas, Shannon Guess Richardson, who had moved to New Boston, Texas, from Jackson County a couple of years ago, also pleaded not guilty to two counts of mailing a threatening communication and one count of making a threat against the president of the United States.

Richardson, an actress, is accused of sending the threatening letters in May to Obama, Bloomberg and a third man who heads Bloomberg’s gun-control group in an attempt to frame her now-estranged husband. Richardson grew up in South Hall County, attending West Hall High School.

She was arrested on June 7. About two weeks later, U.S. Magistrate Judge Caroline Craven ordered her to undergo a psychological exam at the request of Richardson’s lawyer, Tonda Curry.

Curry had said Richardson displayed behavior that raised questions about whether she could help in her own defense. But on Wednesday, Curry told Craven she wouldn’t contest the finding that Richardson is competent for trial.

Richardson appeared in court in an olive-green jail jumpsuit and didn’t speak during the hearing, except to talk with Curry.

Authorities have determined the letters were mailed from New Boston — about 150 miles northeast of Dallas — or Texarkana and postmarked in Shreveport, La.

“What’s in this letter is nothing compared to what ive got in store for you mr president,” the letter to Obama says, according to Richardson’s federal indictment.

The government has accused Richardson of mailing the letters and trying to pin the crime on Nathan Richardson, whom she married in 2011. He filed for divorce earlier this year.

According to an FBI affidavit, Richardson first contacted authorities to implicate Nathan Richardson in the scheme. But she failed a polygraph exam and investigators found inconsistencies in her story, according to the affidavit.

Shannon Richardson, who has had minor television and film roles under the name Shannon Guess, later admitted she mailed the letters but maintained her husband made her do it, according to the affidavit.

If inhaled, ricin can cause respiratory failure, among other symptoms. If swallowed, it can shut down the liver and other organs, resulting in death. The amount of ricin that can fit on the head of a pin is said to be enough to kill an adult if properly prepared. No antidote is available, though researchers have been trying to develop one.

Each charge carries up to five years in prison. Richardson will remain in custody pending a Sept. 11 detention hearing. The judge also set a pretrial conference in her case for Oct. 7.