Ms. Chang said her mother’s response to the letter has not changed since the first time she read it.

“Every time she reads it, it’s the same,” Ms. Chang said. “From the first word she starts crying. She had never seen her father, so it was like he didn’t exist, but when she saw the letter she knew she had a father, and that he loved her.”

While Taiwan’s government has reckoned with some of the traumas of its past — for example, by creating a museum devoted to a notorious 1947 massacre — researchers say far fewer resources have been devoted to chronicling the decades of political repression under the rule of Chiang Kai-shek’s Kuomintang, the Chinese Nationalist Party that ruled Taiwan as a one-party state from 1945 until Taiwan’s first democratic presidential election in 1996.

Academics say that little is known about the mechanics of repression under the Kuomintang, and that there has not been a thorough and transparent examination of the archives. Though researchers believe many records were destroyed, they also believe others have been kept from surfacing through willful neglect.

“We know there are hundreds of thousands of records you can get access to, but there has been no systematic effort to go through them,” said Huang Chang-ling, a professor of political science at National Taiwan University. “What’s the percentage we have seen? It could be 10 percent or 90 percent. I have no idea, and I don’t think anyone does.”