nà ànzi guòqu èrshí duō nián le, dàng'àn shì lǐ fān chūlái de zhǐ dōu fā huáng le

那案子过去二十多年了，档案室里翻出来的纸都发黄了。

That case is over twenty years old, and the papers dug out from the archives have all yellowed.