[Osem]

Police searching for a body at a farm raided in an anti-slavery operation have appealed for the author of an anonymous letter to come forward, saying it could be "vital".

Specialist officers are excavating the site at Marshfield, near Newport.

Four people - three men and a woman - are being held after raids in Cardiff, Monmouthshire and Marshfield on Monday.

Operation Imperial is looking at claims people were kept in poor conditions and forced to work for no pay.

http://www.bbc.co.uk/news/uk-wales-s...wales-24215255