A wealthy couple is targeted for death - but why?

Was a son behind the assassination of his mother and shooting of his father?

Produced by Patti Aronofsky
[This story previously aired on July 16, 2011. It was updated on July 20, 2013.]

On Sunday, Aug. 22, 2004, after a family birthday celebration that included their son, Christopher, his girlfriend, Juliette, and family friend Teddy Montoto, Susan and John Sutton retired to separate bedrooms in their Coral Gables, Fla. home.

Susan often slept in the second room because her husband John snored. Little did they know that about four blocks away, there was a man who had driven up with one intention - to kill them both.

Dressed in all black with a Glock 9 mm semi-automatic pistol, the man shot John, then turned to Susan and shot her six times. But he was not done. The gunman turned back to the master bedroom and emptied the gun into John.

Susan Sutton was assassinated in her bed. John Sutton, shot twice in the head, shockingly survived.

Video: John Sutton's 911 call

Nothing was taken from the house - not money, nor jewelry. There was no doubt that this was a premeditated effort to make sure that they were dead.

Now, the question was who could've done it and why?

Just hours after someone broke into John Sutton's home, murdered his wife, and tried to kill him ... doctors weren't sure he would live.

"Everybody says it was somewhat of a miracle that I survived," John Sutton told "48 Hours" correspondent Troy Roberts. "I lost a tremendous amount of blood... They apparently gave me last rites. They thought that I was gone."

Melissa Sutton was 18, a freshman in college. Her mother was dead and her father had been shot multiple times; twice in the head. When she arrived at the hospital, she says her father was "almost unrecognizable."

"The fact that I knew his hands, and I knew his ears and his skin tone, I could tell that this kind of disfigured person was my dad," she said quietly.

She knew him, but he had a harder time recognizing her. When John Sutton woke up in intensive care, he was blind.

"The magnitude of my injury, the facial pain and the loss of the eyesight was just so huge," he told Roberts.

"You must have been wracking your brain thinking, 'Who could have possibly done this?'" Roberts asked.

"Yes, I certainly was," John replied. "And I thought people were trying to kill me while I was in the hospital. I felt I wasn't safe. I wanted to get out of there. It was one big mess."

John still hadn't heard what happened to his wife.

"I remember asking Melissa, 'How's mom doing?' She had been told by the police not to tell me about Susan," he said. "Later on I was told that she passed away."

Melissa describes her mother as "intelligent" and "confident."

"The kind of person who's in their 40s, but wants to take violin classes, calculus classes, because she just wants to be better," she said.

And more than anything, Susan Sutton wanted to be a great mother. Once the head nurse of a surgical intensive care unit, Susan gave her career up in the late 70s when she and John adopted their first child, Christopher.

"That was the happiest day of her life, it was absolutely the happiest day of her life," said Susan's sister, Mary Marier. "I heard her on the telephone. I could hear her screaming from Florida ... how happy she was and how thrilled she was."

Almost seven years later, the couple adopted Melissa.

"She loved those children," Marier said of Susan. "And she loved them unconditionally."

Those children were now planning their mother's funeral as police scoured the crime scene. Susan Sutton's jewelry and John Sutton's wallet were left untouched on a dresser.

"Take the wallet, easy cash, at least. But nothing was taken. ...This person had a mission," said Miami-Dade Detective Rosanna Cordero.

Detective Cordero hoped John, even with a serious head injury, could help her.

"He remembered bits and pieces. He thought he remembered a figure at the door," Cordero explained. "He might be a black man or wearing all black clothing... he was not sure."

"So with that kind of spotty memory, the information he provided wasn't very helpful?" Roberts asked.

"No, it wasn't."

Cordero thought she'd have more luck with Teddy Montoto, John's law partner. Montoto told the detective he was on the phone with John's wife, Susan, and heard gunfire. So he raced to the scene, arriving just after police.

"I was the one who told him that Susan had died and he was very emotional about it," Cordero recalled.

And then Montoto said something surprising. He told Cordero that he was a marksman and he'd been shooting a gun earlier that day.

"He was a competitive shooter. That's something that he did as a hobby," Cordero said. "That raised our eyebrows."

Detective Cordero immediately sent Montoto's gun in for testing. And she pushed him for more information about his late night phone call with Susan.

"He was not forthcoming with me," said Cordero. She suspected Montoto was hiding something.

"He's asked to submit to a polygraph, which he does and he fails. Especially in regards to his relationship with Susan," said Cordero.

The interrogation continued until Montoto finally revealed his secret.

"He did in fact confess to having a sexual relationship with Susan," she said.

"Did that make him a suspect in your mind?" Roberts asked.

"It did ... Obviously, he has a motive," Cordero replied. "A motive at least to kill John, maybe, not necessarily Susan, but love triangles can drive people to do very extreme behavior."

Teddy Montoto's gun didn't match the murder weapon. And police were able to confirm he wasn't in the Sutton home during the shooting. As for the polygraph, police say he failed because he was covering up the affair, hoping to keep it from John.

Asked how he dealt with the betrayal, John said, "I wasn't very happy about it. Very, very upset."

Up until that point, John and Montoto had a strong working relationship. And their law firm had just gotten one of their biggest settlements ever - over $1 million.

"They had been very successful in their civil litigation and along the way had made some enemies," Cordero explained. "In fact, John had had death threats against him."

Police investigated every one of them - but they all had alibis.

"It was at that point that I started interviewing some of John's closest friends," said Lead Detective Larry Belyeu. He says there was one name that kept coming up.

"They said, 'You need to look at Christopher Sutton.' I said, 'Christopher Sutton, the son?' 'Absolutely,'" he recalled.

Detective Belyeu thought it odd that fingers were being pointed at John and Susan's son, Christopher, then 25 years old. For months after the shooting, Christopher had been by his father's side. And when John finally left the hospital, he moved in with his son.

But police were hearing alarming stories about Christopher.

"He wanted his parents dead," said Cordero.

"He actually choked his mother one time, saying that he could kill her," said Belyeu.

The son who once seemed so devoted ... was now their prime suspect.