Paul Klebnikov, the US-born editor of Forbes magazine's Russian edition, was gunned down outside his Moscow office in July 2004.
Many people believed the killing was connected to the 41 -year-old Klebnikov's work investigating corruption in Russia and the country's shadowy business world.
Ukraine's State Security Service said in a statement today that it has detained a Russian man who was wanted for several slayings, including Klebnikov's. The Ukrainian agency did not identify the suspect.
Three people were charged with the journalist's murder in 2006 and later acquitted. A higher court ordered a retrial for the main suspect, but he absconded before the proceedings could be held.
Klebnikov, a New Yorker of Russian descent, investigated corruption and sought to shed light on the closed, sometimes violent world of Russian business. His family said after the 2006 acquittals they were distressed that Klebnikov's killers remained at large.