Fourteen members of a criminal gang have been convicted of stealing millions of pounds (dollars) worth of rhinoceros horn and Chinese artifacts from British museums and auction houses.

A jury at Birmingham Crown Court in central England found four gang leaders guilty Monday. Ten other men were convicted at previous trials.

The thieves broke into collections including the Fitzwilliam Museum in Cambridge and the Oriental Museum in Durham in 2012, stealing jade items valued by police at between 17 million pounds and 57 million pounds ($24 million and $80 million). Many have never been recovered.

They also tried to steal a rhino head from Norwich Castle Museum, but dropped it as they fled.

The gang was dubbed the Rathkeale Rovers because of its links to the village of Rathkeale, Ireland.