(CNN) -- After deliberating for nearly two hours, a Georgia jury found 18-year-old De'Marquise Elkins guilty Friday of multiple charges, including felony murder, for shooting and killing 13-month-old Antonio Santiago during a robbery.
Elkins was also convicted of aggravated assault and other charges for shooting pastor Wilfredo Calix-Flores during a separate mugging 10 days before the baby was shot.
His mother Karimah Elkins, who was tried along with her son, was convicted of tampering with evidence for her role in trying to cover up the shooting.
Both Elkins and his mother showed no sign of any emotion as the verdict was read. They sat silently, staring straight ahead as they have throughout the entire trial.
Elkins could be sentenced to life in prison for his convictions. He was spared from the death penalty, because he was 17 when the baby was shot. A Georgia law prohibits anyone who is under 18 years old at the time of involvement in a crime from being executed. Elikins' mother could be sentenced to up to 10 years in prison for her conviction.
Sherry West, Santiago's mother, wept on the stand during the trial as she recounted how Elkins shot her son in broad daylight in Brunswick, Georgia, on March 21, after he and another teen tried to mug her.
"I told him I have a baby and I have expenses and I didn't have (money). He asked me if I wanted him to shoot my baby. I told him, 'Please don't shoot my baby.' He shot a warning shot into the ground," West said, weeping. "I asked him, 'Why are you doing this? Please don't do this.' It felt like he shot me in the ear. Then he shot me in the leg. My left leg."
West said one of the teens then did the unthinkable -- he aimed for the baby.
"I tried to stop him. I put my arms over my baby but he still shot him," she said. "He walked over and shot my baby."
During his closing argument Friday, Elkins' attorney Jonathan Lockwood attacked West's recollection of the shooting, saying she couldn't confidently identify Elkins as the shooter. He also accused her of plotting her baby's death to profit from a life insurance policy.
"Sherry West is a woman who was very distraught, who was very emotional. But also who acted in a rather bizarre way. You saw the video of where she is laughing and cutting up with officers, and making jokes with them just after her child was murdered," Lockwood said.
"Incidentally, does anybody know what the protocol is for how you are supposed to act when you watch your child get shot in the face," prosecutor Jackie Johnson said during her closing argument.
Johnson called the defense's accusation that West planned her baby's death a "grand conspiracy" and an attempt to distract from the reality that his client is guilty.
"We have a defendant who preyed upon the weak. He preyed upon the weak when he was looking for Mexicans to rob, because he knows lots of times they can't speak English. They are afraid. They might be here illegally. They may not even report to police," said Johnson. "They don't see any more Mexicans that morning. They see something even better, something even more weak, something even more vulnerable, a mother and a child."
Johnson ended her closing argument with an emotional plea to the jury to find Elkins guilty of murder.
"This case cries out for (determining) malice," Johnson said.
The teenager accused of being Elkins' accomplice is Dominique Lang, who was 15 at the time of the shooting. Although Lang is a minor, CNN is identifying him because he is charged as an adult, and media outlets have been naming him since his arrest.
Lang has also pleaded not guilty to the multiple charges against him, which include felony murder. He will go on trial later, separately from Elkins, and also faces life in prison.
Lang testified against Elkins earlier in the trial, identifying him as the shooter.