About a year ago, the documentary filmmaker Laura Poitras introduced her portrait of the WikiLeaks founder Julian Assange at the Cannes film festival. She was fresh off an Oscar win for her work on “Citizenfour,” which focuses on Edward Snowden, the National Security Agency whistle-blower.

Mr. Assange, who sought asylum at the Ecuadorean Embassy in London, let Ms. Poitras into his inner sanctum. Some critics have praised her film, “Risk,” for its up-close perspective on Mr. Assange, while others have faulted the film’s approach as “an embedded report that sacrifices impartiality for access,” as Catherine Shoard of The Guardian put it.

All the while, Mr. Assange was not lying low, to say the least. His story changed significantly from where Ms. Poitras’s film had left off. And on Sunday, after the season finale of the espionage thriller “Homeland” on Showtime, a teaser for Ms. Poitras’s “Risk” showed that her film has changed, too, in ways that portray Mr. Assange in a far different light.

“This is not the film I thought I was making,” Ms. Poitras says in the trailer. “I thought I could ignore the contradictions, I thought they were not part of the story. I was wrong. They are becoming the story.”

The developments were fairly dramatic. Mr. Assange’s story began with WikiLeaks disclosures in 2010 that were credited with helping bring about the Arab Spring protests and that illuminated civilian deaths in Iraq and an unvarnished view of fighting in Afghanistan, and it includes charges of sexual assault that led to his 2012 asylum request. But soon after the Cannes premiere in May last year, a group of women accused another subject of the Poitras documentary, the privacy activist Jacob Appelbaum, of sexual misconduct. (Both men have denied the charges against them).

And, of course, Mr. Assange and WikiLeaks went on to play a major role in the United States presidential election with the leaks of Clinton campaign emails, and questions continue to surround the organization and its founder over Russian involvement in the leaked materials.

Showtime, which has the premiere rights for “Risk” and intends to show it this summer after a theatrical release, would not divulge the full arc of the film, which has not been completed.

Risk (2017) | Official Trailer | A Film by Laura Poitras

“It was always a work in progress — it was unclear where the story was going to end,” said David Nevins, the president of Showtime. “It’s five years in the shooting and the making of it, and an awful lot has changed in the Julian Assange story.”

Mr. Nevins said he had decided to run a teaser for “Risk” on Sunday night to take advantage of the big audiences he expected for “Homeland,” with which the parallels are obvious. (The previous season included a character very much based upon Ms. Poitras.)

Given the way perceptions of Mr. Assange have whipsawed over the past year in the United States, — going from hero to villain and villain to hero in the conservative and liberal camps — it only makes sense that the film would change.

But with several investigations into Russian involvement in the United States presidential election continuing, deciding where to end the film has not gotten any easier.