Witnesses to a murder in a Snellville parking lot two years ago testify about their accounts of the day a young mother was gunned down after picking up her son in a custody exchange with her estranged husband.

Christine Kurke testified she drove past Heather Strube and the killer when Strube asked for help.

"The larger of the two, a woman, blonde woman said something into my window," said Kurke.

Kurke testified she saw Strube being shot and called police.

A separate witness, Alicia Hines, testified she was in her car with a sleeping child when she saw Heather Strube's husband drive away and then she noticed the young mother putting her son into the car.  Hines says she then saw what she thought was a man confront Strube.

"Had a funky looking wig, was kind of looking backwards suspiciously and then walked around the back of my car," testified Hines.

She says the person pulled something from a bag and shot Strube in the head.

Hines later picked Joanna Hayes from a photo lineup. But, Defense Attorney Bruce Morriss says police never showed her a photo lineup of men.  During cross-examination, Hines admitted she was zero percent sure that person was Hayes.

"I wasn't certain, but the only thing that would call my attention was those eyes," testified Hines.

Police say surveillance video from the scene shows Hayes wearing a wig and fake mustache. She owns a white pickup that police say was spotted parked behind the Target at the time of the murder.

Hayes' son and Strube were in the last stages of a bitter divorce at the time.  In opening statements Wednesday, prosecutors maintained Hayes didn't want custody of her grandson to go to Strube.

"She didn't like Heather, she didn't want Heather to have custody of Carson in the divorce and she did not think Heather was a good mother," says Gwinnett County assistant district attorney Christa Kirk.

But Hayes' attorney Bruce Morriss told jurors that the motive will unravel during the trial.  He maintains police focused on Hayes early on in the investigation and never looked for other suspects.

"Within perhaps 24 hours, they latched onto Joanna Hayes as a suspect and, we're going to suggest, abandoned all fruitful attempts to find the real killer," he says.

Morriss says Strube had a history of gambling and police failed to look at her computer to perhaps implicate someone else.

The trial is expected to last three to four weeks.