Sir Edward Downes died in July
The son of English conductor Sir Edward Downes will not be charged with assisting his suicide.
Director of public prosecutions Keir Starmer said there was enough evidence to charge Caractacus Downes but that it would not be in the public interest.
Sir Edward died on 10 July at the age of 85, after travelling to the assisted suicide group Dignitas in Switzerland.
It is the first case in which guidelines on assisted suicide published last month have been applied.
The guidelines state that anyone acting with compassion to help end the life of someone who has decided they do not want to go on is unlikely to face criminal charges.
Sir Edward and his terminally ill wife, Joan, 74, chose to end their lives together in Switzerland, their family said at the time.
The Metropolitan Police began an inquiry when officers were contacted by solicitors acting on behalf of Mr Downes to report the death of his parents.
'Motivated by compassion'
Police found evidence that Mr Downes had booked a hotel room in Switzerland for his parents and accompanied them overseas.
Mr Starmer said these acts would be sufficient to charge him under the Suicide Act of 1961.
But he explained that there was also evidence that Mr Downes's parents had 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: "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."
Prosecutors were also provided with evidence in relation to Mr Downes's sister Boudicca, but they will not be taking any action against her either.
The Birmingham-born conductor was honoured by four music colleges and five universities as well as receiving the Laurence Olivier, Evening Standard, Critics Circle and Royal Philharmonic Society awards.
He became a CBE in 1986 and was knighted in 1991.