CNN  — 

Former US marine Paul Whelan was convicted of espionage and sentenced to 16 years in prison, a Moscow court ruled Monday, concluding a months-long case that put additional strain to already complicated US-Russian relations.

From behind a glass screen ahead of the verdict, Whelan held up a sign in court with phrases on it including “Sham trial,” “No human rights,” and “Paul’s life matters.”

Whelan then personally called on the US president Donald Trump as well as leaders of Ireland, the UK and Canada to “end this political charade.”

“This is slimy, greasy, grubby Russian politics. Nothing more. Nothing less,” Whelan said.

Whelan – who is also an Irish, British and Canadian citizen – was detained at a Moscow hotel in December 2018 by Russian authorities who alleged he was involved in an intelligence operation. He has been in Lefortovo prison in Moscow since and the trial was held behind closed doors.

His lawyer, Vladimir Zherebenkov, previously said Whelan was unwittingly handed a flash drive containing “state secrets” while on a personal trip to Russia. Russian Foreign Minister Sergey Lavrov has said Whelan was caught “red-handed.”

Whelan denies the spying charges and says he has been denied proper medical treatment while in detention. His family maintains he traveled to Moscow to attend a wedding and was arrested on false charges.

Whelan held up a sign as his sentence was delivered reading "Sham trial," "No human rights" and "Paul's life matters."

Zherebenkov told CNN Monday that Whelan thought he was followed by Russian special services for years, since he first started coming to Russia. According to Zherebenkov, Whelan had many Russian friends, “mostly among military,” and one of his contacts was operating “under the control of special services” and handed him the drive.

Zherebenkov also stoked speculation that Whelan’s sentencing will be used as a leverage by the Kremlin to arrange a prisoner swap for two Russians in US custody, Viktor Bout and Konstantin Yaroshenko.

The lawyer added that the defense plans to appeal the decision. “There were serious hopes for positive outcome but in this case political rationale, negativity towards the US and the games the special services play have led to a sad result,” Zherebenkov said.

Russia’s Foreign Ministry last year raised the possibility that Yaroshenko, convicted of drug smuggling in 2011 and sentenced to 20 years in prison, could be returned “in exchange for any American national” held in Russia. Yaroshenko is serving his sentence at the Federal Correctional Institution in Danbury, Connecticut. Viktor Bout, a Russian arms dealer dubbed the “Merchant of Death” who was sentenced to 25 years in US federal prison in 2012, has also been mentioned.

The Kremlin spokesperson Dmitry Peskov said Monday in a conference call with reporters that Whelan cannot be considered a political prisoner and has been “convicted on charges that were proven in court and accepted by the court.”

The US ambassador to Russia John Sullivan condemned the sentencing as “a mockery of justice” in a statement to media after the verdict.

“If they can do this to Paul, they can do this to anyone. A secret trial with the inability to defend oneself… it’s a mockery of justice in addition to the fact that he’s been horribly mistreated,” he said.

“For all the criticism Russia levied against the United States over the years, including most recently, one thing I haven’t heard criticized is our criminal justice system, the commitment to due process and fundamental rights … to a conviction after a public trial, and Paul has been denied that from the beginning,” Sullivan said, referring to a flurry of critical comments voiced by the Russian officials following the unrest in the US after George Floyd’s death.

The verdict will harm the US-Russia relations, the ambassador added, saying that this case “complicates our process on other matters as well.”

Sullivan said that he had not seen any evidence and Whelan was unable to choose his defense counsel or present witnesses in his defense.

Secretary of State Mike Pompeo demanded Whelan’s immediate release Monday, saying that the US “is outraged by the decision of a Russian court today to convict US citizen Paul Whelan after a secret trial, with secret evidence, and without appropriate allowances for defense witnesses.”

“We have serious concerns that Mr. Whelan was deprived of the fair trial guarantees that Russia is required to provide him in accordance with its international human rights obligations,” Pompeo said in the statement.

Whelan with his lawyers during a hearing at a court in Moscow on January 22, 2019.

“The treatment of Paul Whelan at the hands of Russian authorities has been appalling,” Pompeo added. “Russia failed to provide Mr. Whelan with a fair hearing before an independent and impartial tribunal; and during his detention has put his life at risk by ignoring his long-standing medical condition; and unconscionably kept him isolated from family and friends.”

Whelan’s brother David Whelan told CNN in a phone call Monday that he would like Trump “to bring Paul home.”

“We have been waiting for some action, and we understood that the American government, their hands were tied, because the Russian government wouldn’t speak about a release for Paul until Paul was convicted,” he said.

“But now that the conviction has happened, we really don’t see any reason now for, or any excuse for, a lack of action or lack of request or interaction by the US government, whether it’s President Trump directly or the people who work for him to gain Paul’s release.”

He said Sullivan told the family that Trump is aware of their brother’s case, adding that the US envoy called the family and gave them an update on what happened in the courtroom.

Sullivan was able to exchange a few words with Paul Whelan – “it was just things like, ‘send my parents my love,’ and that he misses them,” David told CNN.

David said that the family had not had any indication that a prisoner swap is under discussion, despite comments from Zherebenkov.

A photo showing Whelan in front of the Kremlin during a visit to Russia in 2006, according to an article on the United States Marine Corps website.

“Prisoner swaps are a Russian approach to justice. And while the Russian government has been clear about what they would like to swap for, which is including access to their diplomatic properties in New York and Maryland, and a number of prisoners who are in American prisons … the American government hasn’t shown any interest in doing a swap for Paul, and they haven’t spoken to us about doing a trade proposal and I’m not sure that we would ask them to do that either,” he said.

“The people in the State Department will have the best idea about whether an exchange or sanctions or some other method is the best way to gain Paul’s release.”

David told CNN the family remain concerned about Whelan’s wellbeing in the wake of his emergency hernia surgery last month and the coronavirus outbreak in Lefortovo prison.

“We’re obviously concerned that between his recovery from his emergency surgery and the virus that he may not be in the best condition,” he said.

David warned against Americans traveling to Russia, noting that: “Paul went to Russia as a tourist and someone who liked Russia, who was interested in their culture and their people, and he has ended up in just a terrible situation and I wouldn’t wish that on anybody going to any country.”

“I hope Americans going to Russia, either put up their visits, until there’s a rule of law established in that country, or are very careful and realize that the peril that they’re putting themselves in,” he said.

Earlier, he said in an emailed statement that the Russian legal system had been “found guilty of injustice.”

“We had hoped that the court might show some independence but, in the end, Russian judges are political, not legal, entities. We understand that Paul’s lawyers may appeal this decision within the next two weeks. We hope that, in their continued search for justice for Paul, that the appeal is successful. But Russians do not expect justice from their legal system, and neither do we,” he said.

“Our family will continue to fight for Paul’s release.”

CNN’s Emma Reynolds contributed to this report.