A body has been found during a search of a rural property for a beloved horse breeder who was allegedly murdered in a case police are struggling to explain.

Phillip Robert Bruce is in custody accused of shooting dead 82-year-old Edwin Dobbin and burying his remains in an attempt to cover up the crime.

Police found a body while searching a property north-west of Sydney on Friday afternoon.

Identification is yet to be confirmed, but the body is believed to be Edwin Dobbin, NSW Police said in a statement. 

The 82-year-old vanished nearly a month ago from a location almost 100km away, triggering a series of missing-person appeals from worried family members.

Bruce, 67, who police said knew Dobbin, was arrested at a Smithfield home on Thursday after allegedly telling authorities conflicting accounts of the elderly man’s disappearance.

Following the arrest, police began searching a site in the Hawkesbury region.

“Police spoke with the family yesterday and obviously in these tragic circumstances they’re very, very upset,” acting Superintendent Tim Calman said.

There is no motive known for the alleged murder, Calman said.

Bruce allegedly killed Dobbin on September 25, the same day he was reported missing, court documents read.

Two missing-person appeals were issued for Edwin Dobbin after he was last spotted at Leppington, in Sydney’s south-west, early that day.

Police and his family said they held serious concerns for his welfare due to medical conditions that required medication.

He might have been seen at two locations in south-west Sydney on the day of his disappearance, including near a petrol station at Prestons.

Dobbin was a prominent miniature horse breeder in Sydney and a maker of sulkies, which are lightweight carts used for harness racing.

Bruce has also been accused of providing a false statement to hinder the investigation, and unlawfully disposing of a corpse.

His matter was briefly mentioned at Fairfield Local Court on Friday, when his barrister Thomas Skinner did not apply for bail.

The case is due to return to Parramatta Local Court in December.

–AAP