The state prosecutor and the judge investigating whether the king's son-in-law Iñaki Urdangarin and his business partner syphoned off public funds remain at loggerheads over whether Urdangarin's wife, Princess Cristina, should be formally named a suspect in the case.
In a writ made public Tuesday, prosecutor Pedro Horrach accused Judge José Castro of pursuing the infanta for who she is, not for what she has done.
"It is a basic principle of criminal law that you cannot implicate or punish anyone for what he is but for what he has done," Horrach said in the writ.
Judge Castro is investigating the now-defunct non-profit Nóos Institute, which was set up by Urdangarin and his partner Diego Torres and received millions of euros for organizing public events.
Castro suspended a previous decision naming the infanta as a suspect following a complaint by Horrach but has continued with his probe into her tax affairs and Aizoon, a property company jointly owned with her husband.
Horrach claimed Castro had shown bias in not extending his probe to Torres' wife.
"In a state of law, when faced with identical circumstances, the judicial response must be identical," his writ said.