When does imaginative writing in a biography become distortion of the truth?

In the context of biography as a literary genre, imaginative writing crosses the line into a distortion of the truth when a biographer invents or suppresses material specifically to create an effect.1

While biography requires an imaginative ordering of facts to transform raw data into a coherent narrative—such as grouping events to reveal personality traits or themes—this must occur strictly within the bounds of verified information. A biographer fails the truth if they manipulate the record to enhance the narrative, yet they fail the art of the genre if they merely recount facts without providing insight or "illumination".1

Ultimately, the biographer’s primary responsibility is to maintain authenticity by rigorously testing the evidence. Successful biographical artists, such as James Boswell, demonstrate that it is possible to provide a compelling, lifelike account of a subject without resorting to the invention of matter or the deception of the reader.2