MARIETTA, Ga. -

The mother of a slain 13-month-old boy testified for hours Tuesday in the trial of a Brunswick 18-year-old accused of fatally shooting her toddler as he sat in his stroller.

Sherry West testified that she was walking back home from the post office with her son, Antonio Santiago, the morning of March 21 when two black males approached her, pulled out a gun and demanded her purse several times. She said when she didn't comply, one shot at her and then shot her baby in the face.

West said the boys ran off as she was trying to perform CPR on Antonio. She said the shooter was tall, black, with full lips and wearing a red shirt.

UNCUT VIDEO:  Sherry West taken back to crime scene

The night of the shooting, West said police gave her a photo lineup where she said she identified De'Marquise Elkins, who's on trial.

Elkins enters Cobb County courtroom She came face to face in court with the person she believes killed her baby.

"I asked him, 'Why are you doing this? Please don't do this,'" West said. "And it felt like he shot me in the ear. Then he shot me in the leg -- my left leg."

"What happened after that?" a prosecutor asked.

"He walked over and shot my baby," West said.

"Do you see in this courtroom today the person who hit you in the ear and shot you in the leg?" the prosecutor asked.

Tim Pulliam Tweets From Courtroom

"Yes," West said.

"Point him out to us," the prosecutor said.

"The boy, the young man in the blue shirt," West said.

"And what else?" the prosecutor said.

"He has a tie on," West said.

"Ms. West, do you see the man in this courtroom today, the man who shot and killed your baby Antonio Santiago?" the prosecutor asked.

"Yes," West said while crying.

During cross-examination, the defense gave West several photos to pick out the shooter. She picked Dominique Lang, the second murder suspect who is not on trial.

The defense also got her to admit she suffers from borderline personality disorder, bipolar disorder, post-traumatic stress disorder and paranoia.

Elkins' attorney, Kevin Gough, told the jury the medications West is on and their potential side effects, which he said include hallucinations, depression, agitation and vision changes.