(CNN) -- A woman accused of helping kidnap Utah teenager Elizabeth Smart from her bed in 2002 apologized to the young woman Tuesday as she pleaded guilty to federal charges.
"I'm greatly humbled as I realize how much Elizabeth Smart has been victimized and the role I played in it," Wanda Eileen Barzee said during a court hearing Tuesday.
"I'm so sorry, Elizabeth, for all the pain and suffering I have caused you and your family," she said, according to a court transcript. "It is my hope that you will be able to find it in your heart to forgive me one day."
Barzee, 64, pleaded guilty in federal court to kidnapping and unlawful transportation of a minor, and she said she will plead guilty in state court to conspiracy to commit aggravated kidnapping. She also agreed to cooperate with prosecutors in the state and federal cases against her husband, Brian David Mitchell, said Brett Tolman, the U.S. attorney for Utah.
The couple is accused of abducting Smart, then 14, at knifepoint from her bedroom in her family's Salt Lake City home in June 2002. Smart was found nine months later, walking down a street in the Salt Lake City suburb of Sandy, Utah, in the company of Barzee and Mitchell, a drifter and self-described prophet who calls himself Emmanuel and had done some handyman work at the Smarts' home.
Smart was not in court Tuesday to hear the apology, but her father, Ed Smart, said afterward, "I certainly believe that Wanda was a victim to a point. But she chose to be that victim. ... I think that was her choice."
Asked about Barzee's apology, Ed Smart said, "I just hope that it was sincere and that she will continue on that track and prove that through the rest of Brian Mitchell's trial, or whatever happens. ... I felt it was sincere. I hope it was sincere."
In exchange for Barzee's cooperation in the prosecution of Mitchell, authorities have recommended a sentence of 15 years in prison.
"We believe a sentence of 15 years is just and fair under the circumstances," Tolman said.
The plea agreement depends on Barzee's cooperation in the case against Mitchell, 56, in state and federal courts, Tolman said. "We will ask that her sentencing date be continued to allow for her continued cooperation with the government. If Ms. Barzee fails to fully cooperate, we will move to withdraw the plea agreement."
Sentencing was set for May 19, but a sentence will not be imposed until Barzee's cooperation against Mitchell is complete, said Melodie Rydalch, spokeswoman for the U.S. attorney's office.
In court, Barzee admitted that she and Mitchell planned Smart's kidnapping and that she encouraged him to carry it out. When he returned to the couple's outdoor camp with the girl, "I aided and abetted Mitchell in the confinement, control and sexual assault of Elizabeth Smart," according to the plea agreement.
Barzee said she also assisted in transporting Smart to California from Utah in October 2002 and back to Utah in March 2003 "with the intent that she engage in sexual activity for which any person can be charged with a criminal offense," according to the agreement.
"Wanda is a person who is a different person than the person who was arrested," defense attorney Scott Williams said after the hearing. "The person she is now is someone who wants to accept responsibility, cooperate."
Barzee had been housed at the Utah State Hospital while courts determined her competency as well as Mitchell's. After years of being declared incompetent, she recently was declared competent to stand trial, according to the Salt Lake Tribune newspaper. A state court had ruled that she could be forcibly medicated, and that ruling led federal prosecutors to proceed with bringing a case against the couple, the Tribune said.
"Today's agreement means that Elizabeth Smart will not have to testify at trial against Ms. Barzee," Tolman said. "It is our belief that this outcome will begin to bring long-awaited closure to Elizabeth and her family."
At a competency hearing for Mitchell last month, Smart, now 21, testified that she had been held captive in Utah and California. Just after her abduction, Mitchell took her to a wooded area behind her home and performed a mock marriage ceremony with her, she said. During the nine months of her captivity, Smart testified, no 24-hour period passed without her being raped by Mitchell.
Mitchell's competency hearing is set to continue November 30. His attorneys asked that it be delayed further, but U.S. District Judge Dale Kimball denied their motion Monday.
Smart, a student at Brigham Young University and a member of the Church of Jesus Christ of Latter-day Saints, testified in October because she was set to leave on a mission, something typical for young Mormon men that is becoming more common for women as well.
CNN's Ashley Hayes and Eliott C. McLaughlin contributed to this report.