JACKSONVILLE, Fla. -

The biological mother of 15-year-old boy who was shot and killed Sunday night at his Westside home is searching for answers to what happened to her son.

Bryan Layfield's stepmother, Christy Files, has been charged with evidence tampering in connection with his death. Police said she changed her story about how her stepson was fatally shot, saying it was accidental and happened inside the home.

"'Sorry, I shot your son. Please forgive me. Put a Band-Aid over it. Get over it,'" said Amanda Helmkin, Layfield's mother. "No, that's not going to happen. Somebody needs to accept responsibility for what happened. Somebody needs to let somebody know the truth. The truth needs to come out."

Layfield lived with his father and stepmother. Helmkin (pictured below), who lives in Savannah, Ga., said she's coping with the loss of her son and still doesn't know exactly what happened.Amanda Helmkin

She said she didn't find out her son was killed until a day later.

"It took his uncle calling my brother to call me and tell me my son is gone," Helmkin said. "I still didn't get answers."

Files (pictured below) initially told police someone shot her stepson in the backyard of their home and she saw two men fleeing over the fence of the backyard after the shooting, according to a police report.

But after investigators found a bloody .22-caliber rifle in the attic of the home, they questioned Files and she admitted that she hid the rifle after the shooting and said she made up the story about the men running from her yard, according to the report.

Helmkin said the unanswered questions make her angry.

Christy Files "His father was a good father but is a convicted felon," she said. "Why is there guns in the house? Why is there guns in this house? Why is there three different guns in this house?"

Layfield's dad pleaded guilty in 2011 to aggravated battery with a dangerous weapon and just last month was arrested for violating probation.

Helmkin said her son would normally spend summers with her.

"I want for somebody to take responsibility," she said. "Somebody needs to take responsibility for this because this is my child, my firstborn, my heart, my whole, my soul. Somebody has to take responsibility for what has happened."

A vigil is being held at 7 p.m. Wednesday at the Melvin Circle home where Layfield was shot.

His funeral is set for 4 p.m. Sunday at Hardage-Giddens Town and Country Funeral Home off Normandy Boulevard.

To help the family with funeral costs, you can donate to the Matthew Layfield Benefit Memorial Fund at Wells Fargo. The account number is 8477780194.