One week after the establishment of the State of Israel in 1948, (and three days before the Israeli Defense Forces were created), a large-scale massacre of more than 200 Arabs allegedly occurred in the Palestinian village of Tantura. This event was one incident in wars from 1947-1949, a period that Israeli Jews call the War of Independence. Palestinians use another term: Al Nakba, or the Catastrophe.

The details of what occurred at Tantura have long been disputed, with some Israeli Jews claiming nothing happened and most reluctant to even talk about it. By not acknowledging the massacre at Tantura, the government has committed to not addressing this issue.

A new documentary by an Israeli director that had its world premiere Jan. 20, the opening night of the Sundance Film Festival, explores what happened. The film by Alon Schwarz – called, simply, “Tantura” — also examines why the Nakba is taboo to discuss in Israel and what happened when one person questioned the details of this event.

Schwarz stumbled upon the story of Teddy Katz, who in the late 1990s had conducted extensive research into Tantura, compiling 140 hours of audio interviews with dozens of Jewish and Arab witnesses to the battles. Based on these oral testimonies, he wrote a master’s thesis at the University of Haifa that argued that the IDF’s Alexandroni Brigade carried out this atrocity.

Though initially well-received by the university when it was submitted around 1998, when his paper went public on Jan. 21, 2000, in the Israeli newspaper Maariv, Alexandroni veterans sued Katz for libel. His thesis was later rejected by the university and his reputation was ruined – Katz also suffered a stroke just weeks before his first meeting in court. The legal case questioned the accuracy of the oral testimonies upon which his assertions were founded. Katz, still alive though in poor health, claims he was coerced to write an apology, which he says is his greatest regret. He recanted almost immediately.

But the audio testimonies remain.