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.

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.

Gough also tried to suggest West may have had a role in the death of her child. He raised concerns about her calling her insurance company the day after the child was killed to inquire about his policy.

West said she was advised by someone to get an insurance policy on Antonio after he had been sick in the hospital in 2012.

The defense is also trying to point to domestic problems between West and the child's father, Louis Santiago, as a possible motive.

Before West's testimony, the trial centered around two witnesses who testified Elkins attempted to rob them with a gun a week before Antonio was shot and killed.

Pastor Wilfredo Calix-Flores and Clever Jimenez-Gomez told the jury they were approached by three young men while they were working outside their church.

Both witnesses said one of the men pulled out a gun and demanded money and cellphones. When they did not cooperate, Calix-Flores said, the robber shot him in the arm.

The victims testified that they identified Elkins from a photo lineup as the shooter after hearing the news the toddler had been shot.

Elkins is charged with attempted robbery in that case unrelated to this trial.

The jury heard from 10 more witnesses Monday as the trial entered its second week.

Prosecutors have said Antonio was killed in a botched robbery and that ballistics and other evidence implicate Elkins. West was also wounded in the shooting.

Among the witnesses Monday was a family friend of Elkins, who testified that the teen hid a gun under their couch the day after the toddler's killing.  Danielle Williams said that later that day, Elkins' mother, Karimah, and sister, Sabrina, went to the house looking for the gun.

"I saw Sabrina lift up the sofa and get the gun," Williams told the jury.

The two women are charged with tampering with evidence, accused of dumping the gun in a pond. Karimah Elkins is being tried simultaneously with her son; Sabrina Elkins will be tried separately.

Also testifying Monday was Willie Merrell, who said he drove the two Elkins women to a fishing pond off Highway 17, saying, "I heard a loud splash."

Brunswick police searched that pond and found a .22-caliber revolver.  They have not said whether that was the gun used to kill the toddler.

Late in the day, a Georgia Bureau of Investigation firearms examiner testified that both Antonio and his mother were hit with .22-caliber bullets, they were from different manufacturers, and he could not rule out that two different guns were involved.

The trial is being held in Marietta because of the publicity the case garnered in the spring. The prosecution was expected to rest Tuesday after West's testimony.

If convicted, Elkins faces up to life in prison.