Gwinnett DA says motive still unclear after brothers allegedly try to kill parents

LAWRENCEVILLE, Ga. — Gwinnett County's top prosecutor says he's never had a case like the one his office is investigating now -- two brothers accused of brutally beating their parents, trying to kill them.
In arrest warrants, police say the younger brother Cameron Ervin repeatedly stabbed his father and tried to strangle his mother. His older brother, Christopher Ervin, allegedly tried to strange his father and "assisted in the stabbing."
The district attorney says the attacks were planned.
"They turned on the gas on the fireplace then lit a candle. Now whether the candle went out or whether the gas, they put the candle up too high? I don't know the exact circumstances," said Gwinnett County District Attorney Danny Porter.
Porter says the brothers then went outside and waited in the cul-de-sac in front of their home for an explosion.
When there was no boom, he says they went back inside and began attacking their parents.
They had already allegedly drugged them with Xanax.  Mother Yvonne was able to slip away and call for help.
"Please send someone to my house. My kids are trying to kill me," Yvonne Ervin said on the 911 call.
Porter says the sons have made statements to police about a bad or difficult home life, but he says there's no evidence so far of that.
"The claims don't, under the circumstances, seem credible. They don't seem believable… battered child or abused child," Porter said.
Younger son Cameron reportedly told officers at the scene, "Just shoot me now. I just tried to kill my (expletive) parents. Who does that?" 
But his attorney Mark Yun insists there is more to the story.
"You've got to understand there is only one person on the 911 call. You are not getting the full story," Yun said.   
Yvonne Ervin had visible injuries to her face when Channel 2 Action News spotted her Monday outside the family's home.
Gwinnett Medical Center confirms her husband Zach was released Thursday afternoon. The two sons remain in jail.
"We are going to try and find out why it happened, but I don't know that we truly will," Porter said.
A preliminary hearing is set for Friday afternoon at the Gwinnett County jail.
Christopher Ervin's attorney refused to comment about the case Thursday and wouldn't say if he would waive the hearing or try to question detectives under oath.