South Wales Police says "new and significant information came to light" which led to the case against John Clifton Davies to be dropped.
He has criticised the force for holding him for 16 months without bail, before finally speaking to key witnesses.
In 2010, South Wales Police launched an investigation into the death of 39-year-old Colette Davies which occurred in India in 2004.
Following a joint investigation with Himachal Pradesh State Police in Northern India and in consultation with the Crown Prosecution Service, a 50-year-old man was charged with her murder and fraud.
During the investigation which continued following the charge, new and significant information came to light which has been reviewed by the CPS.
As a result of this review it has now been decided that proceedings will be discontinued.
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Medication designed for animals was taken from the building in Abertillery on Thursday night.
More than a thousand riders will be taking part in a series of events in and around the town.
Some warm spells of sunshine will develop, although scattered heavy and thundery showers are also expected during the afternoon.