The son of Birmingham-born conductor Sir Edward Downes will not be charged with assisting his suicide, the Director of Public Prosecutions has said.
Keir Starmer said there was sufficient evidence to prosecute Caractacus Downes but it was not in the public interest to do so.
Sir Edward died with his wife, Lady Joan Downes, at the Dignitas clinic in Switzerland on July 10 last year.
The Metropolitan Police launched an inquiry when officers were contacted by solicitors acting on behalf of Mr Downes to report their deaths.
They found evidence Mr Downes booked a hotel room in Switzerland for his parents and accompanied them overseas.
Mr Starmer said these acts would be sufficient to charge him with an offence under the Suicide Act 1961, more commonly known as assisting suicide.
But he added there was further evidence that Mr Downes' parents reached a "voluntary, clear, settled and informed" decision to take their lives.
Mr Starmer said that by helping them Mr Downes was "wholly motivated by compassion". He added: "Although his parents' wills show that Mr Downes stood to gain substantial benefit upon the death of his parents, there is no evidence to indicate that he was motivated by this prospect.
"Other factors against prosecution are that Mr Downes' actions in booking the hotel room can be characterised as of minor assistance and, after reporting the matter to the police, he fully assisted them in their inquiries into the circumstances of his parents' suicide."
Mr Starmer said he took into account new guidelines, which he published in February, that outlined that motive should be at the centre of any decision.
Prosecutors were also provided with evidence in relation to his sister Boudicca Downes, but took no further action against her.