Alexei Navalny shares a light moment with his wife Yulia. File

His 19-year prison sentence was widely condemned by rights groups and in the West as punishment for daring to cross President Vladimir Putin.

Through messages passed through his lawyers, he posted regularly on social media in a characteristically optimistic and light-hearted tone.

Here is what Navalny's final weeks looked like, in his own words:

'Ho-ho-ho'

On December 26, Navalny posted his first message from his new Arctic prison colony, having disappeared for weeks after being moved from his former prison closer to Moscow.

The icy IK-3 prison colony in the Siberian region of Yamal-Nenets, some 2,000 kilometres (1,200 miles) from his native Moscow, would be where he spent his final few weeks.

"I am your new grandfather Frost," Navalny said, in his usual tongue-in-cheek manner.

"I have a tulup, an ushanka and I will have valenki soon," he said, referring to traditional furry Russian winter coats, hats and boots.

"I now live above the Arctic Circle ... But I don't say 'ho-ho-ho, I say 'oh-oh-oh' when I look out the window, where first there is night, then evening, then night again."

Navalny said he was tired from the 20-day journey from his previous prison in the central Vladimir region, close to Moscow.

"Don't worry about me, everything is well. I am so happy that I finally got here."

'Thinking about Leonardo DiCaprio'

A few weeks later, after a spell in quarantine, Navalny shared more details about his conditions in the new Arctic prison.

"The idea that Putin was pleased (enough) that he had put me in a barracks in the Far North that they would stop throwing me in solitary confinement was ... naive," the 47-year-old said.

Prison authorities told him: "'Convict Navalny refused to introduce himself in the correct way'. Seven days in solitary confinement."

Navalny spent more than 300 days in solitary confinement -- or a "punishment cell" as his colleagues called it, based on its name in Russian -- during his three years in prison.

He was ordered there on 27 occasions, often for minor infringements of prison protocol.

Allowed out for a daily walk in the pitch black of at 6:30 a.m., Navalny said: "I promised myself I would go out in any weather."

His cell was "11 steps from wall to wall".

"It has never been colder than minus 32 (Celsius). Even in such a temperature you can walk more than half an hour -- only if you have the time to grow back a nose, ears and fingers," he said in a January 9 post.

"Today I was walking, freezing and thinking about Leonardo DiCaprio and his trick with a dead horse in The Revenant," he said, referring to a scene in which his character crawls into an animal carcass to keep warm.

"I don't think it would work here. A dead horse would freeze to death within 15 minutes."

'I'm Russian'

Navalny also regularly ridiculed prison routines.

On January 22, he said the prison wardens at IK-3 would wake everybody up at 5 a.m. to play the Russian national anthem.

"And right after that -- the second most important song in the country: Shaman's 'Ya Russky,'" he said.

The song -- which means "I'm Russian" -- has become an unofficial anthem for President Vladimir Putin.

"Imagine the scene. Yamal-Nenets region. Polar night. In a penal colony of convicts, prisoner Navalny serving 19 years -- who the Kremlin's propaganda for years has scolded for taking part in Russian marches -- is exercising to 'Ya Russky'".

'Send me money'

In a court hearing on 15 February -- a day before his death -- Navalny was filmed joking with the judge over a stream of fines he had been issued.

"Your honour, I will send you my personal account number so that you, with your huge salary as a federal judge, can send me money," he said, laughing.

"I am running out of cash, and thanks to your decisions, it will run out even faster. So send it!"

'I love you'

Navalny's last post, published on Valentine's Day, was dedicated to his wife, Yulia.

"Baby, you and I have everything, just like in the song: cities, airfield lights, blue snowstorms and thousands of kilometres between us," he said, quoting a popular Soviet-era tune.

"But I feel that you are near me every second, and I love you more and more."

Agence France-Presse