The body of an elderly woman was found following a tip-off from an activist who conspired to blackmail her family.
Police began searching the woodland after a tip off
Gladys Hammond's grave was robbed in October 2004 by extremists who admit targeting a family-run farm which bred guinea pigs for medical research.
John Smith, 39, of Wolverhampton, one of four being sentenced, told police where the body was, a court heard.
The three others are Jon Ablewhite, 36, of Manchester, Kerry Whitburn, 36, and Josephine Mayo, 38, both of Birmingham.
All four, who are being sentenced at Nottingham Crown Court for their part in a six-year blackmail campaign against the Hall family, are expected to receive long jail terms.
Ablewhite, Smith and Whitburn have been told they can expect 12 years. Mayo has been told she can expect six.
Opening the case against them, Anthony Glass QC said the robbing of the 82-year-old's remains from a churchyard in Yoxall, Staffordshire, was "the most outrageous event of the campaign" against the family.
The campaign also included protests outside the farm, a burglary in which 600 guinea pigs were freed and threats to family members, friends and employees.
"Towards the end of the conspiracy, the prosecution case is that the three male defendants were concerned with the digging up of the grave and subsequent retention of the body of Gladys Hammond," Mr Glass said.
"In fact, in the last few days, her body has been found and returned to its rightful place.
"It was found on Cannock Chase. It was found as a result of confirmation provided by the defendant Smith.
"Otherwise it would never have been found."
A witness noticed the grave at St Peters Church had been desecrated on the morning of 6 October, 2004.
Mr Glass gave the court details of the chronology of events and evidence which linked the three male defendants to the intimidation campaign.
These include typed letters sent to the Hall family and their employees.
Cleaner May Hudson received a letter threatening to desecrate her late husband's grave if she did not leave the firm.
The letter read: "Anthony will rest in peace. We know where he is, it's up to you whether he stays there."
Other letters gave the Hall family instructions about how Mrs Hammond's remains could be recovered.
Mobile phone evidence
One read: "Gladys's return to you is not an indefinite offer. You need to bring closure to this issue.
"Stage one is to announce your intentions to close."
The family were to place an announcement in an East Midlands publication with a phone number and date for closure, the letter said.
They would then receive map co-ordinates of Mrs Hammond's location.
"We also wish to see Gladys returned to her rightful resting place but mess us around and this will be the last you hear from us on this issue," the letter said.
Mobile phone evidence also linked the three male defendants to a visit they made to woods near Newchurch following a BBC Crimewatch appeal.
The purpose of the visit was to either make sure the remains stayed buried or to move them, Mr Glass said.
Smith, of Leicester Street, Wolverhampton; Whitburn, of Summer Road, Edgbaston; Ablewhite of Hawley Street, Levenshulme; and Mayo, of Spring Bank Road, Edgbaston all admit conspiracy to blackmail between September 1999 and September 2005.