Tampa, Florida -- A 53-year-old former military linguist and longtime Army officer's wife was convicted Thursday of first-degree murder, with jurors rejecting the argument that she was legally insane when she shot and killed her 13-year-old son and 16-year-old daughter more than three years ago.
VIDEO: Julie Schenecker verdict
Julie Schenecker wiped her nose and eyes, then the bailiffs handcuffed her as the verdict was read in just under three hours of deliberations. She started to cry. She was sentenced to two life terms to be served at the same time.
Schenecker, killed her daughter, Calyx, and son, Beau, in January 2011 while her now ex-Army officer husband, Col. Parker Schenecker, was on a 10-day deployment to the Middle East.
VIDEO: Juror speaks while leaving courthouse
Before the judge sentenced her, Schenecker said, she takes responsibility for what she's done.
Through tears she said, "I know I shot my son and daughter. I don't know why. But I have time to try to understand that."
If she had been acquitted by reason of insanity, she would be committed to a mental hospital until doctors and a judge agree that she is no longer a danger to herself or others.
She also said she believed in the U.S. judicial system and would accept her sentence.
VIDEO: Julie Schenecker speaks before sentencing
Earlier, prosecutors said Schenecker wrote in her journal that she wanted to kill herself and wanted to be cremated with her children, their ashes mixed together. She mentioned that she was going to try to move her son's body into her bed and wanted to die next to him.
Before she was sentenced, she talked about her children.
"I know our children are in heaven. I want people to try to find comfort in believing as I do that they are in no pain and they are alive and enjoying everything and anything that heaven has to offer...Jesus is protecting them and keeping them safe until we get there."
Parker Schenecker and his mother looked sad and exhausted as the verdict was read. Julie Schenecker's sister cried softly.
VIDEO: Parker Schenecker speaks following verdict, sentencing
All six mental health experts who testified said Schenecker was mentally ill, but three experts called by prosecutors said she was legally sane when she shot her children.
Defense attorneys said Schenecker is so affected by bipolar disorder and depression that she doesn't know right from wrong. Under Florida law, the inability to tell right from wrong is one of the criteria for a not guilty by reason of insanity plea.
Her attorney, Jennifer Spradley, told jurors they needed to do is consider Schenecker's state of mind when she pulled the trigger, that she was suffering from such severe depression and manic depression that she didn't understand what she was doing.
"Her mind is clouded. She didn't choose this illness — it chose her," Spradley said. "When she wasn't sick, she was a good mother."
Experts testifying for the prosecution say the longtime military wife was calculating and deliberate when she bought the .38-caliber handgun days before the killings, along with more-lethal hollow bullets. But in her journal, she lamented the three-day wait for a background check, writing she had planned a weekend massacre.
Prosecutor Jay Pruner told jurors in his closings that Schenecker was "desperate, depressed, angry, but very determined." He said she was despondent over what she thought was the inevitability of divorce from her husband of 20 years.
"These were deliberate, well-planned, well-implemented and well-concealed homicides," Pruner said.
SEE ALSO: Interview with Schenecker alternate juror