Polish Prime Minister Donald Tusk says a suspect has been detained in connection with the murder of Russian opposition artist Semyon Skrepetsky, who was allegedly using a Georgian passport.

Tusk announced the detention in a post on social media.

“Police in Lublin and Poland’s Internal Security Agency have detained a suspect in the murder of a Russian citizen in Biała Podlaska, who was using a Georgian passport. Law enforcement authorities are now working to identify the organizer of the crime,” the Polish prime minister wrote.

Russian opposition artist Semyon Skrepetsky was killed in Poland on June 15. The 44-year-old artist was known for his sharp criticism of Russia’s political leadership. He was shot five times in the city of Biała Podlaska.

Earlier, two Belarusian citizens were detained in connection with the murder, but they were later released.