Missoula, Montana (CNN) -- In a dramatic turn during her murder trial, newlywed Jordan Linn Graham pleaded guilty Thursday to second-degree murder in a plea deal and recounted how she pushed her new husband over a Montana cliff last summer.
"It was a reckless act," she told the judge who demanded the truth of what happened to Cody Johnson, her husband of eight days, in Glacier National Park in July.
"I just pushed," she stated.
The newlywed couple was arguing when he grabbed her and she told him, "Let go."
She thought he was going to hold her down. She put one hand on his back and another on his shoulder and then pushed him face-first to his death, she told the court.
When Graham declared her guilt, the victim's mother in the gallery crumpled in her seat.
Another relative of Johnson, who was 25, threw her head back and cried, whispering "she said guilty." His friends held hands and appeared satisfied.
Graham, 22, now faces a sentence of up to life in prison, U.S. District Judge Donald W. Molloy said. Her minimum sentence could be 235 months, or 19 1/2 years, though sentencing guidelines are flexible, the judge said.
In exchange for her guilty plea, prosecutors dropped a first-degree murder charge and a lying to investigators charge.
The deal was announced after the prosecution and defense rested their cases and took a courtroom break. They hadn't yet begun their closing arguments to the jury.
When the trial resumed, the judge said there were new developments, and the prosecution announced a deal had been made.
The jury was not in the room when the deal was announced.
Lead defense attorney Michael Donahoe said prosecutors offered the deal in the late morning before the lunch break. Graham accepted the deal, he said.
When everyone returned to the courtroom, the judge asked Graham if she was sure she wanted to plead guilty, because she could end up spending the rest of her life in a federal prison.
Graham consented to the proceeding, though she appeared overwhelmed. She didn't cry, however.
When the judge first asked what happened the day her husband was killed, Graham responded, "I wasn't thinking of where we were."
Then she spoke of the deadly argument and how she had misgivings about the marriage.
"I wasn't really happy," she said.
She wasn't feeling like one should when first married, she said.
When the judge asked her why she left the murder scene, she said she was scared of what had happened. She had the car keys in her pocket.
The judge accepted her guilty plea. Graham, a resident of Kalispell, was then handcuffed in the courtroom and taken into custody.
Her sentencing is scheduled for March 27, 2014.
Another of her attorneys, Andrew Nelson, summed up the trial and its surprise outcome: "For us, it's been emotional from the drop of the gavel."
A close friend of the victim, Brad Blasdel, was terse about justice in the case as he left the courthouse: "God'll take care of it."
During the U.S. District Court trial this week, prosecutors contended that Graham was having serious second thoughts about her marriage before her husband's death and willfully lied to police after it.
But her defense lawyers argued that the death plunge was an accident resulting from an argument. Graham initially lied to police, they said, because she was afraid she wouldn't be allowed to explain what happened on the cliff's edge.
The defense presented to the jury an emotional, heartbreaking review of the couple's wedding video and showed the couple as a normal pair preparing for marriage.
Graham's husband disappeared July 7. Four days later, the FBI said, Graham led friends and relatives to a popular spot in the park, where they found Johnson's body.
Graham at first maintained that she had simply speculated Johnson might have gone there. But an FBI agent said that she changed her story when she was shown a surveillance photo of the couple entering the park together.
CNN's Jack Hannah and Kyung Lah contributed from Montana, and Michael Martinez wrote from Los Angeles.