SYRACUSE, N.Y. -- It was a suicide call to Onondaga County Sheriff's deputies in 2007 that led to the arrest of Stacey Castor. She had been under investigation for the death of her husband, David Castor, since he died in 2005. David Castor died of poisoning from an component used in anti-freeze.

In September of 2007, Stacey Castor was arrested after reporting that her 20-year-old daughter, Ashley Wallace, attempted to commit suicide at their home in Clay. It was a suicide attempt investigators didn't buy into at the time. They said an issue of public safety forced them to arrest Stacey Castor.

When officials got to Castor's house that day, they say Wallace was found with a note confessing to killing David Castor, as well as Stacey

Castor's first husband, Michael Wallace, in 2000. Michael Wallace also died from poisoning.

At first, it was believed that Michael Wallace died of a heart attack, but his body was exhumed and a second autopsy revealed he died of poisoning.

In 2007, Wallace told the Syracuse Post-Standard she thought her mother drugged her and said she thought her mother wrote the confession note.

Castor has been charged with second-degree murder and attempted murder.

ABC's “20/20” has cameras set up in the Onondaga County Court House and will be airing a special segment about the trial.

Castor is being investigated for the possible murder of her first husband, but no charges have been filed.