Morgan said that handwritten notes found in the suspects' car made reference to "decapitate," another read "Jocelyn RIP" and a further note said: "Once Jocelyn's dead ... find a river to dump her."
The motive for the plot was not clear, but Morgan said the men may have targeted Stone for her money or because they disliked her links with the royal family. The notes indicated that the pair disapproved of Stone being invited to the Prince William and Kate Middleton's wedding in 2011, he said. The defendants deny all charges. The trial continues.
Stone rose to fame in 2003 with her multi-platinum debut "Soul Sessions" album. The set established her as one of Britain's biggest young female stars. A string of U.S. top 10 albums would followed.