Thirteen members of an organised crime gang with Irish links - dubbed the Dead Zoo Gang - are facing jail after plotting to steal a rhino horn and Chinese artefacts worth up to €73m.
A jury convicted four of the gang's "generals", who helped to plan and oversee a string of offences, including break-ins at Cambridge's Fitzwilliam Museum and Durham's Oriental Museum in the UK in 2012.
John 'Kerry' O'Brien Jr (26), Richard 'Kerry' O'Brien (31), Michael Hegarty (43) and Daniel 'Turkey' O'Brien (45), were found guilty after a trial which could not be reported because of similar offences committed by travelling criminals dubbed the 'Rathkeale Rovers'.
The two-month hearing at Birmingham Crown Court was told that 10 other men had previously been convicted for their parts in the conspiracy, which included a bungled attempt to steal a rhino head from Norwich Castle Museum.
Although jurors heard that exhibits stolen in Durham and Cambridge were valued at around €21.7m, detectives believe they might have fetched up to €73m on the "booming" Chinese auction market. The gang masterminded an offence at Gorringes Auction House in East Sussex, and organised the disposal of stolen artefacts.
Eight of the men convicted after a four-year international police inquiry have family or business links to Rathkeale, Co Limerick. The latest trial was told that a computer used to make incriminating internet searches was found at a house in the town.
Other defendants from Cambridgeshire, London, Southend-on-Sea, Wolverhampton, Kent and Belfast either admitted the offences or were found guilty.
They included six members of the same Rathkeale family, travellers' rights campaigner Richard Sheridan, and Donald Wong, a London-based "fence".
Sheridan (47), Wong (56) and Richard O'Brien denied taking part in the plot between September 2011 and August 2012.
Hegarty, John O'Brien and Daniel O'Brien, all of Orchard Drive, Smithy Fen, also denied any involvement in the offences but were unanimously convicted. None of the 18 jade exhibits stolen from Fitzwilliam Museum have been recovered, but a bowl and figurine stolen in Durham were found.
One of the men convicted has been jailed and served his sentence. The other 13 offenders will be sentenced in April.