Even after 30 years, erasing the history of the massacre in Tiananmen Square remains an obsession of the Chinese Communist Party. To a degree, it has succeeded: The Chinese raised in the extraordinary boom times since that day often know little about what happened on June 4, 1989, or accept the official line that curbing the “counterrevolutionaries” was needed to facilitate the economic miracle.

But those who were there, and many of those who know what happened when the Chinese Army crushed the two-month-old democracy protests, cannot forget — and cannot accept that anyone else should. One of them is Jiang Lin, a former military journalist, who was in the square that night and has been consumed ever since by what she witnessed, and who shared her agonizing memories in a series of interviews with The Times’s Chris Buckley.

Ms. Jiang is 66 now, and she left China last week . Had she not, it is very likely that she would have shared the fate of the many other Chinese who have been repressed because their conscience would not let them stay silent. “The pain has eaten at me for 30 years,” she said. “Everyone who took part must speak up about what they know happened. That’s our duty to the dead, the survivors and the children of the future.”

Hers is an anguish and a mission shared by many people around the world scarred by great atrocities, whether survivors of the Holocaust; or relatives of the “disappeared” in Argentina; or those who carry the memories of the Soviet gulag, the Armenian genocide in Ottoman Turkey , the Khmer Rouge killing fields of Cambodia, the massacres in Rwanda or any of the other mass murders of modern times.