A new documentary about Anthony Bourdain has sparked a debate over its use of artificial intelligence to stitch together voiced quotes by the late celebrity chef and effectively bring his voice back to life.

Roadrunner: A Film About Anthony Bourdain, directed by Morgan Neville, takes an intimate look into the life and death of Bourdain, including his global fame, career and pursuit of happiness.

In a recent interview with the New Yorker, Neville revealed that he used AI to synthetically create a voiceover reading of an email by Bourdain himself.

There were a total of three lines of dialogue that Neville wanted Bourdain to narrate, the film-maker explained in his interview. However, because he was unable to find previous audio, he contacted a software company instead and provided about a dozen hours of recordings, in turn creating an AI model of Bourdain’s voice.

In the movie there is a scene about an email sent by Bourdain to his friend, the artist David Choe. Bourdain writes, and viewers hear his voice read aloud: “My life is sort of shit now. You are successful, and I am successful, and I’m wondering: Are you happy?” But the voice was in fact created by AI.

Neville added: “If you watch the film … you probably don’t know what the other lines are that were spoken by the AI, and you’re not going to know.”

Despite Neville describing his use of AI technology as a “modern storytelling technique”, critics voiced concerns on social media over the unannounced use of a “deepfake” voice to say sentences that Bourdain never spoke.

Among those upset with the use of AI was Bourdain’s ex-wife Ottavia Bourdain. She disputed Neville’s claims that he had received her blessing to use the artificial technology, tweeting: “I certainly was NOT the one who said Tony would have been cool with that.”

Sean Burns, a film critic for Boston’s WBUR, denounced the film-makers, writing: “When I wrote my review I was not aware that the film-makers had used an AI to deepfake Bourdain’s voice … I feel like this tells you all you need to know about the ethics of the people behind this project.”

Neville, however, insisted that there was no manipulation, saying: “I wasn’t putting words into his mouth. I was just trying to make them come alive.”

With AI on the rise, the measures employed by the new documentary have once again raised questions about storytelling ethics. As deepfakes become more advanced, critics worry over a growing slippery slope surrounding what is real and what is fake.

Nevertheless, the criticisms do not seem to concern Neville.

“We can have a documentary-ethics panel about it later,” he said to the New Yorker.