Aleksei Navalny, the charismatic anticorruption crusader and persistent thorn in the Kremlin’s side, has published exposés exploring the wealth of Prime Minister Dmitry Medvedev, Defense Minister Sergei Shoigu, Kremlin spokesman Dmitry Peskov, and Prosecutor-General Yury Chaika.

Now he and his investigative team have trained their sights on someone even higher: President Vladimir Putin himself.

Navalny on August 30 released a new video examining a Russian island near the Finnish border where a venerable country house has been restored and, he alleges, used by Putin for holidays.

The 50-hectare property, located on the islet of Lodochny, not far from the city of Vyborg, in a bay north of the Gulf of Finland, is home to several buildings and a helicopter landing pad, according to Navalny. It also has a decades-old mansion known as Villa Selgren, which was used for a 1980s Soviet film about Sherlock Holmes.

WATCH: Aleksei Navalny On 'Putin's Secret Dacha' (In Russian)

Navalny alleged the mansion was restored, beginning around 2010, under the direction of Ilya Traber, who he charged was involved in a legendary Russian organized crime group known as the Tambov Gang. Traber was one of several Russians named by Spanish authorities in a 2016 arrest warrant targeting the gang.

Navalny said land records showed the property belonged to Oleg Rudnov, a Putin confidant from St. Petersburg who headed a company called the Baltic Media Group.

Rudnov headed another company belonging to another Putin confidant, classical musician Sergei Roldugin, who has been alleged by the Panama Papers investigative project to be a conduit for some of Putin’s secretive wealth.

Rudnov also reportedly has ties to Bank Rossiya, a financial holding company headed by Yury Kovalchuk that has been sanctioned by the United States.

Rudnov's son Sergei took over his father’s business holdings after his death in 2015.

'Putin Museum'

Navalny said another building on the island had been restored as a "museum for Putin," with photographs and other paraphernalia dedicated to the Russian leader. He also said his investigators had located an online résumé of the property's main engineer, which listed other projects he had worked on, including an official presidential residence on the Black Sea.

The Kremlin did not immediately comment on the latest Navalny report.

Adding credence to Navalny's video is a report by the independent TV channel Dozhd (Rain), released earlier this week, that also investigated the property and the houses on it, and came to similar conclusions.

Dozhd said Rudnov, in addition to other long-standing connections, also had business ties with Kirill Shamalov, a tycoon who is reportedly married to Putin's daughter.

With his youthful charisma, biting wit, and singular focus on the problem of Russia's endemic corruption, Navalny has risen from obscurity as a lawyer to become a nationally known figure. He's faced multiple criminal prosecutions for cases that his supporters say are political motivated.

The latest one concluded in February and left him with a conviction and a suspended sentence, which effectively bars him from challenging Putin in a presidential election in March 2018.

Still, Navalny has pledged to press on. In June, he helped organize nationwide protests that were among the largest since Putin first came to the presidency 17 years ago.

Underscoring his continuing popularity, the latest Navalny video garnered nearly a half-million views on YouTube within just a few hours of its release.

