Past perfect

Von Petzinger couldn’t be sure that she 5 found / had found an example of early writing but early writing didn’t just appear.

As she documented the symbols, she 3 began / had begun to notice a pattern.

She found that 65 percent of the signs were the same, so she 4 concluded / had concluded that they were a kind of language for communication.

Other researchers 1 noticed / had noticed these geometric signs before von Petzinger visited the caves,

but she 2 was / had been the first to document them.