Retired Army Colonel Parker Schenecker testified in defense of his ex-wife today, who faces first-degree murder charges for killing their two teenagers.

Julie Schenecker has pled not guilty by reason of insanity, and her ex-husband attested to her decades-long battle of mental illness that culminated in the murders on January 27, 2011.

Parker told the court that he noticed symptoms of depression in Julie at the beginning of their 20-year marriage, but that she was a good mother to their children, 16-year old Calyx and 13-year old Beau, when they were young.

In a taped conversation with Tampa police after her arrest, Julie made similar statements.

"I loved them when they were birth through six," she told Detective Gary Sandel.

As the children got older, however, their relationship became turbulent.

"My daughter, the 16-year-old, is mouthy. She calls me names," Schenecker explained.

Parker testified that he knew his wife was receiving psychiatric treatment throughout the years, but he did not have access to her medical files. Attorneys for Schenecker say she suffers from depression and bipolar disorder with psychotic features.

Schenecker told Det. Sandel that one day, her issues with the children came to a head.

"I just topped over. The last straw," she said.

Schenecker shot her son, Beau, twice in the head while she was driving him to soccer practice because he was "talking back" to her.

The military debriefer turned housewife then drove back home, went into her daughter's room, and shot Calyx in the head while the girl was on her computer. Schenecker left Beau's body in the minivan.

Parker was deployed at the time of the murders, and filed for divorce months after Julie's arrest.

He testified Tuesday that his ex-wife had mentioned suicide in the past, but she did not discuss acting on it.

Julie expressed suicidal ideations during her 2011 interrogation.

"Beau went first, Calyx went second. I'd sure as hell like to go third," she told police.

If found not guilty by reason of insanity, then Schenecker will be released from a mental institution after she is deemed no longer a threat to herself or others. If she is found guilty on two counts of first-degree murder, then she will receive a life sentence.