Roderick Newall, 27, sailed away in his father's yacht after the death in 1987 of Nicholas Newall, 56, a Lloyd's underwriter, and his wife, Elizabeth, 48, of St Brelade, Jersey.
In Brazil he met a woman to whom he confessed, in 1991, the court was told.
Desmond de Silva QC, for the prosecution, alleged that the killings were carried out by Mr Newall and his brother Mark, 26, a financier, in October 1987 at their parents' house after celebrating Mrs Newall's birthday. The couple's bodies have not been found.
Mr de Silva told the second day of extradition proceedings that Mr Newall's confession had been triggered by reading from The Glass-Bead Game, by Herman Hesse. The passage began: 'Oh] he thought in grief and horror, now I am guilty of death.'
The court heard earlier that in July 1992 Mr Newall had met his uncle and aunt in Perthshire and given what amounted to a confession.
The Newall brothers inherited an estimated pounds 500,000 in 1991 after winning an application at Jersey's Royal Court in St Helier to have their parents presumed dead.
Roderick Newall, who denies the murders, was arrested at sea by Jersey police in August 1992 and taken to Gibraltar, the nearest Crown colony. Jersey authorities are seeking his extradition to the Channel Islands to stand trial with his brother, who was arrested in Paris last March.
The hearing was adjourned until today.