The man was in his 80s and dying. The woman was 73 and held his hand. They each lost a son in the 1989 Tiananmen Square crackdown and fought for decades to get China to acknowledge the deaths.

But Duan Hongbing wouldn't live to see that day.

"I held his hand and told him that I won't give up," the woman, Zhang Xianling, said she told Duan on a visit to his Beijing hospital bed. She said he squeezed her hand and closed his eyes in response, no longer able to speak. He died last year, a few days after that promise was made.

As the Tiananmen anniversary approaches Friday, the aging parents of victims fear their cause will die with them. The oldest of the Tiananmen Mothers, as the group is called, is 94 years old. The group's leader, retired professor Ding Zilin, says more and more members die each year.

"Can it be that you really want to wear us all down or wait for our deaths so that the problem will naturally disappear?" the group wrote in an essay addressed to the Chinese government and made public this week through the New York-based group Human Rights in China.

At the end, the 128 families who signed it attached the names of 22 former signers who have died....