Witness claims Ga. mother discussed "perfect murder" before fatally shooting daughter-in-law

(CBS/WGCL) GWINNETT COUNTY, Ga. - Prosecutors in Georgia claim a mother plotted the "perfect murder" for months to kill her daughter-in-law, who was in the middle of a divorce and custody battle with the mother's son.

Police say Joanna Hayes shot and killed Heather Strube outside a Target department store in Snellville on April 26, 2009. Strube's toddler sat nearby, strapped in his car seat.

Investigators say Hayes shot Strube while dressed in disguise as a man, wearing a mustache and wig.

On Friday, Paul Pinzino, a former co-worker of Hayes, testified that Hayes told him a year-and-a-half before Strube was killed, how she would commit the "perfect murder."

"She would use a revolver ...because they don't jam," Pinzino testified according to CBS affiliate WGCL.

He also told jurors Hayes told him how she'd melt down the murder weapon.

"I know she said she had a shop behind her house, so she said she could actually use the tools in that shop to destroy the weapon," Pinzino said in court.

Prosecutors believe the motive for the killing was that Hayes wanted her son to get custody of the boy.

Hayes' defense attorneys have told jurors that police targeted the wrong person in their quest to quickly solve the high-profile murder.

According to WGCL, Hayes' son, Steven Strube, is expected to take the stand Monday.