The US former marine was expected to return home on Sunday. Instead, Whelan has been detained in a Russian prison over spy allegations.
The brother of a dual British-US citizen held in Russia on suspicion of spying fears it could take years for him to return home.
Former US marine Paul Whelan has been detained in a Moscow prison since December 28. The 48-year-old was taken into custody by Russia’s Federal Security Service and faces charges of espionage.
"... It clearly could take months and, unfortunately, maybe even years before we get him home", David Whelan, brother of the former marine", told Euronews.
The former marine went into Russia with a US passport, but he also holds Canadian, Irish and British passport too.
David Whelan was somewhat hopeful of the case: "Next week, the British and I expect the other governments, will be making contact with Paul so they will have eyes on him, which will is very heartening. It makes us more confident that it will be difficult for the Russians to mistreat Paul or abuse his rights."
The brother said that through US embassy staff, the family has received an update on Paul's state in prison. David said his brother is in "good health and in good condition", though due to language limitations, as he does not speak Russian, he was unable to request glasses that he needed for his sight, until six days after his detention. Whelan has also been able to receive money from the family to buy toiletries in prison via a money transfer mechanism through the US State Department.
Paul Whelan was supposed to return to the US from Russia on Sunday, according to his brother. His family states he is innocent of the spying charges and was in Russia to attend a wedding.
However, the image of the former marine has become increasingly complex. For years, Whelan had an active profile on the Russian social media platform VKontakte and his four passports have raised suspicion.
Added to that, The Washington Post reported Whelan was found guilty of attempting to steal $10,000 (over 8,000 euros) worth of currency from the US government while deployed to Iraq in 2006. Whelan was subsequently discharged in 2008 from service for bad conduct.
Asked about those details that came to light, his brother said: "we all hide things that don't reflect well on our better selves and I think I was disappointed that Paul had not left the Marines under a normal discharge".
Adding he was " just sad that he had had to hide this from all of us. As far as I know, no one in the family knew that he'd been discharged with the bad conduct discharge. So, I was surprised about it."
The case risks enflaming tensions between the US and Russia. On Saturday, Moscow accused Washington of detaining the Russian citizen Dmitry Makarenko on the Northern Mariana Islands on December 29 and had moved him to Florida.
Paul Whelan was supposed to return to the US from Russia on Sunday, according to his brother. His family states he is innocent of the spying charges and was in Russia to attend a wedding. Adding that as he had a "low-level understanding" of Russian, he doubts the allegations.
"There's universal agreement in the family and in the press that whatever Paul is, he's not a spy," he said.