A 24-year-old woman was arrested yesterday by detectives investigating a hate campaign waged against the owners of a guinea pig breeding farm.
The woman was detained at her home in Wolverhampton by officers investigating the theft of a pensioner's body from a graveyard in Yoxall, Staffordshire.
Police said she was arrested on suspicion of conspiracy to blackmail David Hall and Partners - which operated the farm in Newchurch, breeding animals for medical research - and others.
Four other people have been charged with conspiracy to blackmail the farm owners.
Three of them - John Ablewhite, John Smith and Kerry W hitburn - have been remanded in custody.
The fourth, Josephine Mayo, has been released on conditional bail.
All four are due to appear at Nottingham Crown Court on March 6 for a plea and directions hearing.
A 63-year-old woman, from Burton-upon-Trent, who was arrested in December on suspicion of conspiracy to blackmail answered her bail on Monday and was released without charge, police said.
Guinea pig breeding operations at Darley Oaks Farm ceased last month following a six-year campaign of intimidation by animal rights extremists.
The Hall family announced the closure on January 20 and said they hoped the decision would prompt grave-robbers to return the body of a relative.
The remains of 82-year-old Gladys Hammond, the mother-in-law of Christopher Hall, who co-owns Darley Oaks Farm, were dug up and removed under cover of darkness from St Peter's Church in October 2004.