Grenadian sprinter Bralon Taplin has failed in a Court of Arbitration for Sport (CAS) appeal against his four-year ban from athletics.
The 28-year-old was sanctioned by the Caribbean Regional Anti-Doping Organization in November for avoiding a drugs test.
It followed an incident at the Grenada Invitational Athletics Competition on April 13 of last year, when Taplin won the 400 metres.
He then reportedly left the stadium without completing doping control, despite being informed that he was to undergo a drugs test.
Taplin, who finished seventh over 400m in the Rio 2016 Olympic final, is said to have left Grenada the following day, taking "an early flight home".
In his appeal to CAS, he argued that he should be made immediately eligible to compete on the grounds that he had not been properly notified that he had been selected for the doping control test.
However, CAS described the claim that "he was never approached, followed or accompanied by anyone from the Grenada NADO" as "implausible".
Taplin's ban began on September 25 2019, when he was provisionally suspended.
"Considering all of the evidence accepted in this procedure, the sole arbitrator was comfortably satisfied that the athlete was guilty of the offence of evading sample collection," CAS said.
As well as the Olympics, Taplin has competed at events including the World Championships, the World Indoor Championships and the Commonwealth Games.
He was one of two from Grenada in the Rio final, alongside Kirani James, the London 2012 champion who won silver behind South Africa's Wayde van Niekerk.
The race saw Van Niekerk set a world record.