Woman murdered allegedly by her son in San Tan Valley. Niece says she thought it was a “sick Halloween prank.”

SAN TAN VALLEY, Ariz. – A relative of a woman who was murdered, allegedly by her own son, is speaking out about the tragic ordeal.

The body of 38-year-old Mary Collier was found Wednesday morning in a field in… San Tan Valley.

Authorities said the investigation included a hoax kidnapping call from the son.

The family is still struggling with this.

It’s almost unheard of crimelosing a loved one, allegedly at the hands of another loved one.

READ MORE: Woman Found Dead In San Tan Valley; son charged with murder: PCSO

“She was such an incredible person,” Rebecca Hatch said through tears.

Rebecca Hatch was her niece.

‘I didn’t believe it at first’

Collier was found by a jogger in a field in San Tan Valley on Wednesday morning, October 30.

Investigators believe her 18-year-old son killed her.

“I didn’t believe it at first. I thought it was a joke, some kind of sick Halloween joke,” Hatch said. “Tragically, it turned out to be true.”

‘She was so passionate about her faith’

Her aunt was the family’s caregiver, putting everyone else’s needs above her own and relying on her faith to make it happen, Hatch said.

“She was a Mormon. That’s something I think she wants people to know. Mary was a Mormon in the strongest sense of the word. She was so passionate about her faith. She is so dedicated to it and she touched the people around her. and she inspired them with the way she was. She was selfless,” Rebecca said.

The big question is why? Rebecca says the family can’t understand it, especially because the mother and son always seemed so close.

“Of all the people in the family, Mary was the one he loved the most; she was the one he respected the most. It’s inexplicable. It’s completely incomprehensible and it comes completely out of nowhere,” says Rebecca.

She adds that the entire family will soon come together and find a way to move forward, honoring Mary’s life by following in her footsteps.

“I’m sure if I could have heard her last word it would have been about her family, about the people she loved,” Rebecca said. “That’s the kind of person she was.”

Collier was found by a jogger around 9 a.m. Wednesday in a farm field west of Gantzel Road and south of Skyline Drive. Her body lay in an open field and behind piles of dirt.

Her cause of death is believed to be due to blunt force trauma from a sharp object.

Investigators said they believe the killing stemmed from an argument Tuesday night that continued into Wednesday morning. However, they were unable to determine a motive for the crime.

For those who want to move the family forward, a GoFundMe was founded to raise money for her funeral.