Local police have reportedly found an unmanned all-terrain vehicle as the search for the doctor who treated jailed Kremlin critic Alexei Navalny continues.

Unmanned ATV Found

 According to Russian news agency TASS, a source from the press service of Russia's interior ministry said "a missing ATV was found 6.5 km from the hunting base."

Alexander Murakhovsky, who treated Navalny first after he was poisoned with a Novichok nerve agent, was first reported to have gone missing Saturday.

Omsk local police said Murakhovsky was last seen Friday, after leaving a hunting base using an all-terrain vehicle. The regional interior ministry of Omsk said in a statement that search groups have been dispatched to find a man who disappeared in a forest.

The statement added that hunting inspectors, volunteers, the national guard and police are involved in the search, but that searching has become "complicated by the difficult terrain, the presence of wetlands."

Navalny and Murakhovsky's Ties

Navalny was admitted to the acute poisoning unit of the Omsk emergency hospital on Aug. 20 last year. He was on a plane to Moscow when he fell ill, forcing an emergency landing.

At the hospital, Murakhovsky, then chief doctor, told the media that Navalny's main "working diagnosis" was a sharp drop in his blood sugar due to a metabolic disorder.

Following his hospitalization, Navalny said Murakhovsky lied about the diagnosis. "You like, fake test results, are ready to please the bosses in any way," he wrote on social media.

After getting treatment in the Siberian hospital, Navalny was transferred to Berlin. Murakhovsky reportedly tried to keep the opposition leader from getting transferred at that time.

In the German hospital, doctors confirmed that Navalny was poisoned. Back in Omsk, Murakhovsky was promoted to become the Omsk region's minister of health.

Flashback to February

This isn't the first time a doctor linked to Navalny has been on the news.

In February, a top doctor at the Omsk emergency hospital, Sergey Maximishin, died. At the time of his death, the hospital said in a statement that Maximishin "suddenly" passed away.

Maximishin was the deputy chief physician at the said hospital when Navalny was brought in. A spokeswoman for the Omsk regional health ministry said "preliminary data" showed the doctor died from a heart attack.

No further details or a direct cause of death were provided by the hospital.

Shortly after news of Maximishin's death emerged, Navalny's chief of staff, Leonid Volkov, said that the deceased doctor "knew more than anyone else about Alexey's condition so I can't dismiss possibility of foul play."

Amnesty Restores Navalny's Status

Meanwhile, human rights advocacy group Amnesty International recently said it would restore Navalny's status as a "prisoner of conscience."

The said status was stripped from Navalny in February. Amnesty apologized for its "wrong decision" and for the "negative impacts" the stripping of Navalny's status had on the Kremlin critic and other activists "who tirelessly campaign for his freedom."

Navalny is in jail and recently went through a weeks-long hunger strike to demand for access to his personal doctors. In the latest photos from a hearing, Navalny looked gaunt but still defiant.

Russian officials have denied allegations that Navalny was not provided proper medical care. They said Navalny refused as he insists to get treated by a physician of his choice.