A Tampa mother who is accused of killing her two teenagers told a detective that her children had been "really mean" and she hoped they were dead.

"I loved them when they were birth through six," Julie Schenecker told Tampa Police Det. Gary Sandel in January 2011.

But they became "sassy" as teens, she said, especially her daughter.

"I just topped over. The last straw," Schenecker said in the interview, a recording of which was played in court Wednesday. "My daughter, the 16-year-old, is mouthy. She calls me names."

Prosecutors said Schenecker killed the daughter, Calyx, and her 13-year-old son, Beau. She has pleaded not guilty by reason of insanity to two counts of first-degree murder. If convicted, she will face a life prison sentence without parole; prosecutors declined to seek the death penalty.

Schenecker, who is now 53, also told Sandel how she met her husband, Parker Schenecker, while both served in the military and said she worked as a military debriefer in the Army before having children.

During the interview, her voice was slow and slurred. She said she had been in therapy and took multiple prescriptions, including Lithium for bipolar disorder.

She told the detective that she had long thought about suicide.

"I feel horrible. I just feel horrible," she said. "But I've been thinking about doing this for a long time."

Schenecker's attorneys say she has suffered from bipolar disorder and depression for decades.

During the interview, Schenecker did appear confused at times.

"Are my kids coming in later?" she asked the detective.

Later, the detective asked her where her kids were. She said that Calyx was in her bed where she had placed her after the shooting, and that Beau was in the family's minivan where she had shot him.

"I hope they're dead," Schenecker said to the detective. "What do you think?"

"They're dead," Sandel replied.

Schenecker detailed how she had intended to kill herself after she killed her teens, but wasn't able to articulate why she didn't.

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

Tampa Police officer Fred Arnold testified that Schenecker's mood was "jovial" the day of her arrest.

"She wasn't sad or anything like that," Arnold said. "She wanted me to give her my gun so she could finish the job."

Prosecutors say the slayings were premeditated and point to Schenecker's journal and the fact she purchased a gun days before the shootings as evidence.

Prosecutors rested their case Wednesday. The defense was expected to begin presenting its case on Friday.

Defense attorneys questioned the detective about whether he should have proceeded with the interview of Schenecker because she seemed shaky, impaired and couldn't easily stand on her own.

Parker Schenecker sat in the court for the testimony. The couple was married and he was deployed in the Middle East at the time of the slayings. They divorced months after Schenecker was arrested.