For fugitives on the run, time is running out. Check out " The Hunt with John Walsh " Sundays at 9 p.m. ET/PT and #JoinTheHunt

(CNN) Police blame a bloody family feud for the shooting death of a 39-year-old mother of two outside her upstate New York home.

Four years after the attack, a hunt continues for the suspect: her 77-year-old father-in-law.

The story behind Tammy Palmer's death started innocently enough, with run-of-the-mill conflicts that many families deal with every day. Her marriage to John Palmer followed in the footsteps of her older sister Denise Pannirello, who had married John's older brother Clarence Palmer.

Tammy and John Palmer lived in a quiet, wooded neighborhood about 40 miles north of New York City, on property owned by John's father, Eugene Palmer. Eugene not only owned the property, he lived next door. Both houses sat near a huge state park wilderness area.

After having two children, Tammy and John began having problems.

They started seeing other people but decided to maintain the marriage and "remain friends for the children," John said.

But the marriage worsened. Tammy got a restraining order for John to stay away from the property.

"My father sat back looking at all this and it was not right to him," Clarence Palmer told CNN's "The Hunt with John Walsh."

JUST WATCHED Son helps police search for fugitive father Replay More Videos ... MUST WATCH Son helps police search for fugitive father 01:17

Family members said his rationale was: If my son can't live on the property, why should she be there?

After that, the relationship between Tammy Palmer and her father-in-law turned into a tit-for-tat war, relatives said.

There were accusations of Eugene shutting off electricity to Tammy's house and stories of Tammy intentionally waking up Eugene by blowing her car horn outside his home.

'He just didn't like her'

"He just didn't like her," said Tammy's sister Denise Pannirello. "He didn't like her."

Then their feud got even worse. Much worse.

Tammy threatened to divorce Eugene's son and sue Eugene for his land as part of the settlement.

On September 20, 2012, Eugene allegedly confronted Tammy outside her home with a handgun and tried to hit her in the face.

Eugene told police Tammy had hit him with a stick, but her story was that she had allegedly picked up a log to defend herself.

John Palmer disputes allegations that his father ever owned a handgun.

'I heard a shot, a lot of screaming'

Four days later, 911 operators received an emergency call: "I heard a shot, a lot of screaming, another shot, no more screaming and another shot. ... I think it came from the Palmers'."

Haverstraw, New York, police detective Michael Cruger said Eugene Palmer had been hiding in the woods waiting for Tammy to finish taking her youngest child to the bus stop. On her way back, as she walked up the driveway toward the house, he shot her in the arm. "The first shot — he shot her arm in half ... [according to] the report that we received," said Tammy's father, John Pannirello.

Then, "She ran to the front door," John Pannirello said. "She couldn't get in. There was blood all over the door. She ran to the side door. Blood all over the side door. She tried to run to the back, from what I understand, he fired another shot. He missed."

"She ran around to the back yard, where she collapsed," said detective Cruger. "Eugene stood over her and shot her."

"It was almost like hunting a deer," Cruger said.

"They found her in the backyard," said Denise Pannirello. "I can't imagine. She was probably so scared. She died all by herself."

The escape

After the shooting, Clarence Palmer said, his father fled the scene "with the clothes on his back and a pair of slippers. He didn't even have shoes on."

Cruger said Eugene Palmer drove across the street to his sister's home. He "gave her money to pay the taxes. [He] said, 'Pay the property taxes. Give me an hour before you call the police.'"

Later she told news reporters on camera that Eugene had said, "I shot and killed Tammy. I've had enough."

"That was the last time anybody seen him," said Clarence Palmer.

The manhunt

A widespread, coordinated manhunt turned up Palmer's truck the next day, about a quarter mile from the crime scene.

Bloodhounds tracked a trail from the truck to a campsite in the surrounding state park. From there, dogs led police to a road, where the trail stopped cold.

Cruger said he believes that's where a vehicle may have picked up Palmer and escaped the area.

Clarence Palmer disagrees. He thinks the dogs got confused and made a mistake. "He didn't get picked up by anybody. Nobody would hide him."

Although Denise Pannirello and her father John Pannirello believe Eugene Palmer is still alive somewhere, because he was in "great shape for his age," Clarence Palmer believes the opposite. "He went into a diabetic coma, I believe, and he died," Palmer said.

Cruger said cadaver dogs searched all relevant parts of the approximately 45,000-acre park. "Anywhere he would be," Cruger said.

The search turned up nothing. "We just can't search the entire park," he said.

The fugitive

Eugene Palmer

Age: 77

Height: 5 feet, 9 inches

Weight: 220 pounds

Charged with murder

On the run since 2012

The victim

Tammy Palmer

Age: 39

Children: 2

Tammy Palmer was gunned down outside her upstate New York home in 2012.

The victim's widower and fugitive's son

"I wish I'd never met her because then I'd never fell in love with her and I never would have married her and she never would have been here," said John Palmer, the fugitive's son and widower of the victim. "In a sense they killed each other because I assume that my father's dead and the reason that he would be dead is because he killed my wife."

John Palmer

The victim's sister

"People say it gets easier. It doesn't get easier," said Tammy Palmer's sister, Denise Pannirello. "It gets harder. My sister deserves justice."