While her parents listened to the proceedings via long-distance telephone, federal magistrate Kevin Chang accepted Ferguson's plea agreement in which two counts of acts of terrorism in the original indictment were dropped.

Ferguson's sentencing is scheduled for 3 p.m. Sept. 22 before federal Judge Helen Gillmor.

Ferguson admitted today in court that she left two threatening notes in a bathroom aboard the Legend of the Seas. She will be returned to the custody of federal marshals until travel arrangements can be made to release her to the custody of her parents.

Under the agreement, Ferguson must remain at her parents' home under the supervision of Los Angeles authorities. She will wear a global positioning satellite tracking device.

Assistant U.S. Attorney Ken Sorenson said that one of the reasons the prosecution agreed to the home incarceration before her sentencing is that Ferguson is seven months pregnant.

A $5,000 cash bond must be posted by May 19.

Among the conditions of her supervised release is that she have no contact with her boyfriend.

Ferguson had been charged with two counts of threatening acts of terrorism. Each count carried a maximum prison sentence of 10 years.

She was traveling with her parents and siblings aboard Royal Caribbean's Legend of the Seas when crew members found threatening notes April 22 and 23. Authorities diverted the ship to O'ahu waters so it could be searched and crew and passengers interviewed.

The ship, with nearly 2,400 people on board, was on a 10-day trip out of Ensenada, Mexico.

About 120 federal, state and military investigators searched the ship for biological, chemical, radiological and explosive materials.

None was found and the ship resumed its trip.

Ferguson's father, who owns an auto repair shop in Mission Viejo, Calif., had spent two years planning the 10-day cruise to Hawai'i for the family, the Los Angeles Times reported last month. He took on nearly $7,000 in credit-card debt to make it happen.

"I should not feel guilty about it, because my daughter did it and I had no control over it," said Ferguson, 52, of Laguna Hills. "But as a family, I am sorry for the inconvenience, disappointments, extra work put on by the cruise line, everything."

In the terror notes, Ferguson threatened to "kill all Americanos abord," officials said.

Ferguson told the Times he and his wife had struggled with Kelley since her junior year at Laguna Hills High School, when she started skipping classes to be with her boyfriend, Joshua Brashear, now 23. She dropped her old friends and stopped attending church with her parents every Sunday.

Within a year, she had enrolled in a program of independent study, but her father said he isn't sure she ever graduated.

She moved in with Brashear and got a job as a waitress at a restaurant where he was a waiter.

Ferguson acknowledges friction between the parents and Brashear, whom he nicknames Velcro because the two are inseparable. But Kelley was looking forward to the trip, and despite a last-minute hitch the morning of April 18, when the family left to catch the cruise ship in Ensenada, Mexico, she appeared to join willingly, he said.