A Florida man, who was three years old when his witnessed his father kill his mother and dig her grave, has spoken about discovering her skull in the backyard.

Aaron Fraser told investigators at the time that his father, Michael Haim, had 'hurt' his mother Bonnie, 23, and had buried her somewhere.

'He buried my mom. We digged [sic] it, the hole,' a social worker read from a notebook, where Fraser recounted what had occurred when he was just three.

Years later, he and his brother-in-law were renovating the family home when he came across a plastic bag that he thought contained a coconut while digging in the yard.

'I picked it up... I didn't know what it was. I gave it to Thad. He was looking at it. We looked back in the hole and we could see some teeth,' Fraser told Dateline's Dennis Murphy.

'And then... you could see the top portion of her eye socket on the skull, and everything kind of clicked and we stopped what we were doing.'

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Aaron Fraser (pictured), who was three years old when his witnessed his father kill his mother and dig her grave, discussed what it was like to discover her skull in the backyard

Bonnie Haim, 23 (pictured, with Fraser), disappeared from her North Jacksonville, Florida, home in January 1993

Her husband, Michael Haim, claimed his wife left their home without their son late one night after they had an argument about their marital problems. Pictured: Haim, left, with Bonnie and Fraser as a baby

Fraser, who was adopted into another family and had his last name changed, won the deed to the childhood North Jacksonville home in 2014.

Up until then, it had been rented out.

He and his brother-in-law Thad decided to fill in the backyard swimming pool and remove the outdoor shower.

The pair rented a small excavator in December 2014 and got to work. They accidentally broke a pipe near the outdoor shower and had to find the leak.

'We started digging up against the house, so I see a piece of plastic,' Fraser told Murphy.

'I think when I was digging with the shovel, I broke the bag, and I was like: "Oh that weird, there's a coconut in [the bag]. Why would someone bury a coconut in here? Why would someone bury a coconut in a bag right here?"'

That's when they found the skull.

According to the Florida Times-Union, when Fraser couldn't get hold of his wife, or the case's original investigator, his brother-in-law called police.

In 2014, Fraser won the deed to the home and began doing restoration work in the backyard, where he found a skull and teeth (center)

After the remains were confirmed to be Bonnie's, Haim was arrested at his home in North Carolina in 2015. Pictured: Haim in court

He was convicted of second-degree murder in April and sentenced to life in prison in May. Pictured: Haim, left, in court with his attorneys

Bonnie disappeared in January 1993. Her purse was found in a hotel trash bin, and her car was abandoned near the Jacksonville International Airport in Florida.

According to an arrest affidavit, Haim was abusive, and his wife had made plans to leave the home with her son while he was away on a trip.

Haim claimed his wife left their home without their son late one night after they had an argument about their marital problems. But he didn't notify law enforcement about her disappearance.

Law enforcement wasn't told about the disappearance until a maintenance worker found her purse and called police.

Haim had initially been called a suspect in the case, but he was never charged.

He was arrested in 2015 at his home in North Carolina after authorities confirmed the skull that his son had found was Bonnie's.

Fraser said that at the time of Haim's sentencing that 'justice needed to happen'. Pictured: Haim, left, with Bonnie and Fraser

'He buried my mom. We digged [sic] it, the hole,' a social worker read from Fraser's notes as a child. Pictured, left to right: A social worker reading the note, Fraser, and his adoptive mother

A medical examiner concluded she died from a homicide 'by unspecified means,' according to the arrest affidavit.

A spent shell casing found where Bonnie was buried was the same type of caliber as a rifle that Michael owned, the affidavit added.

In April 2019, Haim, 52, was convicted of second-degree murder and, last month, he was sentenced to life in prison.

'I always believed he killed her and that justice needed to happen, but even today, when the judge said he's going to have a life sentence, it wasn't this great emotional feeling that I had,' Fraser told First Coast News at the time.

Dateline airs on Fridays on NBC at 10pm ET/9pm CT.