SPRINGFIELD -- A Georgia man killed his father and brother with a shotgun as they slept, then shot his mother in the face because of a family feud over the defendant’s affair with his slain brother’s wife, a prosecutor told jurors Wednesday.

The murder trial of Craig Heidt, 42, opened Wednesday in Effingham County with prosecutor Michael Muldrew telling the jury of a crime “as old as the Bible” -- of brother killing brother, and their parents caught in the crossfire.

“It was the lust that he had for his brother’s wife and the money he could get access to,” said Muldrew, who told jurors in his opening statement that Heidt stood to gain from his brother’s $3.5 million life insurance policy.

The August 2008 slayings of Philip Heidt, a prominent real estate developer and former chamber of commerce president, and his 32-year-old son and business partner, Carey Heidt, stunned this suburban community northwest of Savannah.

So did the arrest nine months later of Craig Heidt, who Muldrew said described himself as the “black sheep” of the family. He was an avid hunter but didn’t work, claiming disability from a back injury.

Heidt faces life in prison if convicted. His trial could last through next week.

Heidt’s defense attorney, Dow Bonds, told the jury Wednesday the affair did happen but insisted Heidt was innocent of killing his family. He said police based their case on circumstantial theories rather than physical evidence.

“He’s been charged with these crimes mostly because of gossip, rumor and conjecture,” Bonds said. “No eyewitnesses linked him to this crime... There’s no fingerprints, no DNA linking him, no blood.”

Prosecutors say what drove Heidt to kill his own family -- except his mother, who survived a shotgun blast to the face -- was a rift caused by their discovery that he was sleeping with his brother’s wife, Robin Rast Heidt.

A distraught Carey Heidt moved into his parents’ home. Philip Heidt threatened to write his adulterous son out of his will. About two months before the slayings, Muldrew said, a family argument became so heated that guns were drawn.

“It’s just a pot that is about to boil over,” Muldrew said. “How is he going to have Robin? His parents are never going to agree to it. Carey’s in the way. He’s jealous of his brother and his success.”

He said Heidt crept into his parents’ home in the middle of the night using a key and armed with a shotgun. He shot his brother as he slept, then moved to his parents’ bedroom. Heidt’s father was shot while trying to pull bed sheets over his face.

The suspect’s mother, Linda Heidt, came out of a bathroom after hearing shots. A blast of buckshot tore off her lower jaw.

She not only survived but managed to reach her cell phone and call 911. However, she was unable to identify her attacker -- either to the 911 operator or Wednesday on the witness stand.

“I had trouble getting them to understand me, because my mouth had been shot,” Linda Heidt said. “They asked me did I know who did it, and I told them no.”

She said she was unconscious for about four weeks after being shot. She testified that after she regained consciousness, her son seemed only to be “worried about me, as protective as he could be.”

Prosecutors say police never recovered a gun, but found three unfired shotgun shells in Craig Heidt’s truck containing the same type of buckshot used in the slayings. They also found bruises on his shoulder that could have been caused by recoil from a shotgun.

Authorities say Craig Heidt began living with Robin Heidt and her three children weeks after the slayings. When he was arrested in May 2009, the couple planned to move to Charleston, S.C., and had bought wedding rings.

Robin Heidt wasn’t charged in the slayings. But in February she was arrested on charges of threatening a witness.

Bonds, Craig Heidt’s attorney, said others likely had motives to hurt the Heidt family. The real estate collapse put a financial strain on the family business, he said, that could have turned past associates into enemies.

“Nobody knows who committed this crime,” Bonds said. “The unfortunate fact is the truth will never be known.”