Boris Nemtsov was a prominent member of the opposition in Russia and an extremely vocal critic of president Vladimir Putin's regime. He had previously served under president Boris Yeltsin in the 1990s.
Last week, he was shot four times in Moscow city centre. He died at the scene. As of yet, no arrests have been made in connection with the murder, but it has been widely speculated that it was orchestrated by Russian authorities, as Nemtsov was said to be on the verge of releasing a damning report on Russian military involvement in eastern Ukraine.
Sandra Kalniete, a vice-chair of parliament's EPP group, travelled to Moscow to attend his funeral, only to be denied entry into Russia.
Speaking to the Parliament Magazine, she explained, "they asked me to wait and withheld my passport. After about two hours, the authorities informed me that I was denied entry into the country".
The Latvian deputy says that when she asked why this was happening, the authorities cited a law without being able to tell her what it stated, simply telling her, "these are the rules".
"Putin is directly or indirectly responsible for Nemtsov's killing - it was a turning point for Russia in its relationship with the rest of the world, because before killings were more discreet, more orchestrated, but this was blatantly out in the open, in a highly secured area near the Kremlin under the federal security services' cameras"
Despite not having been provided an official explanation, Kalniete does have her own theory, conceding, "I have always had a very strong and clear position on the annexation of Crimea and the illegality of the attack - in my speeches, I often condemn the hybrid war which Russia is conducting in Ukraine".
She underlines that, "when the EU and the US sanction a person, they make this public and inform the ministries for foreign affairs of the countries concerned. In Russia, they never make their so-called blacklist public - this means that theoretically, any EU citizen can discover at the airport that they are denied entry into Russia".
While Kalniete insists that what happened to her was "just a small incident", she reveals, "what I experienced made me think about those very courageous people who are standing for their convictions, who are true patriots of Russia - members of the opposition, civil rights defenders, dissidents - and who are prepared to pay the highest price, as Boris Nemtsov did".
She adds, "I have great sympathy and admiration for these people - they are at the mercy of Russian authorities.
The MEP warns, "there is another dimension which is increasingly dangerous - the wave of hate which is created by Putin's regime and which grasps the majority of the population, hate towards any person who has a critical opinion of Putin or is pro-European, or simply different - they are perceived as enemies of the state by the general population, and that is very dangerous".
In her view, "Putin is directly or indirectly responsible for Nemtsov's killing - it was a turning point for Russia in its relationship with the rest of the world, because before killings were more discreet, more orchestrated, but this was blatantly out in the open, in a highly secured area near the Kremlin under the federal security services' cameras".
"This just shows that Putin is passing on a message of threat to anyone who opposes him, and that he does not care what people outside his country think", she says.
Beyond being denied entry into the country, Kalniete highlights that "the question is about the future of EU-Russia relations - are we prepared to have a realistic approach to the danger we are facing? This is not just for one month or one year - things will only change if the regime changes".
She calls on the EU to "strengthen our defence capacities - they are extremely low", adding that, "we must strengthen our unity in the face of imminent danger coming from Russia".
In her view, the issue lies in the fundamentally different way in which Europe and Moscow approach international relations. She says, "in Europe, we see a relationship with any third country as a win-win, based on international law and cooperation. But in Russia, the concept is different. They see it as, 'we win when you lose', which is a 19th century approach and not tailored for globalisation".
Unfortunately, this difference in opinion is nothing new. Having served as Latvia's foreign affairs minister from 2002 to 2004, Kalniete reveals that "Russia has always been a difficult neighbour and partner".