Enrique Olivares broke into the house of Luis Bárcenas, the former treasurer of Spain's ruling Popular Party (PP) in October 2013.
Armed with an antique revolver and posing as a prison chaplain, he took the family of the imprisoned former treasurer of Spain's ruling Popular Party hostage for over an hour.
During the siege, he pulled out the weapon and demanded family members hand over "a pen drive to oust the government".
Those demands came in the midst of a very high profile and long-running corruption case involving Bárcenas.
The former top official claims to have operated a secret slush fund for Spain's ruling PP before the party came into office in 2011 — allegations repeatedly refuted by Spanish Prime Minister Mariano Rajoy.
Questions also remain over whether the PP wiped hard drives at their party headquarters in Madrid to hide evidence of the so-called "second set of books".
Bárcenas himself is appearing in court on Thursday to answer questions about the matter, after a High Court judge recently ruled there was sufficient evidence of the existence of the slush fund.
In the case of Olivares, prosecutors are now seeking an 18-year-old jail term for the man who took Barcanas' wife and grown-up children hostage.
On Wednesday, the defendant interrupted court proceedings saying voices in "my head won't lave me in peace", a claim which experts dismissing, saying he was merely pretending.
But the lawyer representing the false priest said the priest believed himself to be "a modern-day Robin Hood" and was indeed mentally disturbed.
While Olivares did not have a "psychotic personality" he did have a "different way of seeing and feeling things from most people", the legal representative added.
"He feels threatened by the current social reality and doesn't see it as just. He thinks that people aren't happy with the situation, but aren't doing anything.
"That's why he set himself up as a saviour," the lawyer explained.
The lawyer claims his client cannot be charged as a result.