FORT LAUDERDALE, Fla. — If the woman accused of sending death threats to a Palm Beach County man whose 6-year-old son died in the Sandy Hook school shooting had shown up in court on Wednesday, she probably would have been sentenced to house arrest and probation.

Lucy Richards, 57, of Brandon, near Tampa, was due in federal court in Fort Lauderdale for a change-of-plea hearing and sentencing.

But early Wednesday morning, Richards called the Federal Public Defender’s Office and said she would not be appearing in court.

“Miss Richards called my investigator and said she’s not coming,” Assistant Federal Public Defender Robert Berube told the judge. “That’s all I have.”

Senior U.S. District Judge James Cohn issued an arrest warrant for Richards and canceled the hearing. He also revoked her bond.

“Did she give a reason?” the judge asked.

“No,” Berube said. He told the judge his office gave Richards a written and verbal notice of the court hearing.

Richards’ next hearing will be scheduled after she is arrested.

Richards had been free on bond since she surrendered in court in December. She pleaded not guilty to four federal charges she sent threatening email and voicemails to Lenny Pozner in January 2016. Each of the charges carries a maximum punishment of five years in federal prison. Richards may now face a prison term because she failed to show up and prosecutors could withdraw the plea agreement offer.

Pozner’s 6-year-old son, Noah, was killed in the 2012 mass shooting in Newtown, Conn., which left 20 children and six adults dead.

Richards, a former waitress who is receiving Social Security disability payments, told investigators she sent an email and left several voicemails after she became angry. She said she had been browsing websites that promote false conspiracy theories, prosecutors said.

“You gonna die, death is coming to you real soon,” was one of the voicemail messages left, according to court records. And an emailed message included the words: “Look behind you it is death.”

Some people linked to the Sandy Hook massacre have reported they were harassed by conspiracy theorists who claim the incident, and other mass shootings, were staged by the government to try to erode support for gun rights. But Richards said during an earlier court appearance that she owns no guns and had never even touched one.

Pozner has worked to debunk the conspiracy theories and he set up a website, www.honr.com, and a network of volunteers who report harassment on social media and other websites.