Updated

The ex-husband of a woman accused of killing her two teenagers is on the witness stand in her Tampa, Florida, trial.

Defense attorneys on Tuesday called Parker Schenecker as a witness.

He and Julie Schenecker were married in January of 2011, when police say she shot and killed their 16-year-old daughter Calyx and their 13-year-old son Beau in the family's home.

The couple divorced after the deaths.

Parker Schenecker told the jury Tuesday that his wife's depression and mental illness was a constant "drum beat" in their relationship.

Schenecker is charged with two counts of first-degree murder. The state is not seeking the death penalty and contends Schenecker knew right from wrong when she bought a gun and shot her children.