In 1983, Thomas Keneally's adapted his book "Schindler's Ark" into a 220-page script. His adaptation focused on Schindler's numerous relationships; Keneally admitted later that he did not compress the story enough. Steven Spielberg hired Kurt Luedtke, who had adapted the screenplay of "Out of Africa" (1985), to write the next draft. Luedtke gave up almost four years later, as he found Schindler's change of heart too unbelievable.
During the time when Martin Scorcese was attached to the project as director, he hired Steven Zaillian to write a script. When he was handed back the project, Spielberg found Zaillian's 115-page draft too short, and asked him to extend it to 195 pages. Spielberg wanted more focus on the Jews in the story, and he wanted Schindler's transition to be gradual and ambiguous instead of a sudden breakthrough or epiphany. He also extended the ghetto liquidation sequence, as he "felt very strongly that the sequence had to be almost unwatchable." Together with Spielberg, he conceived the scene where Schindler witnesses the ghetto liquidation, with the focus on the red-coated girl. Zaillian would be awarded the Oscar for Best Adapted Screenplay for the resulting 1993 film.
A veteran go-to script doctor in the industry, Zaillian has contributed to screenplays uncredited on a number of projects over the years. They include "Patriot Games" (1992), "Crimson Tide" (1995), "Twister" (1996), "Primal Fear" (1996), "Amistad" (1997), "Saving Private Ryan" (1998), "Black Hawk Down" (2001), "Road to Perdition" (2002). and "Body of Lies" (2008).
"The similarity between the big directors I've worked with is that they allow the writer to find a way of doing what they want done without saying, 'Do it this way.' They describe what they want, then let the writer figure out a way to do it." (IMDb/Wikipedia)