Author Murong Xuecun summoned by police over Tiananmen Square event
The author had earlier pledged to turn himself in on his return from Australia.
"On the surface the government appears to be stronger than ever … yet it is actually so fragile that its leaders lose sleep when a few scholars meet and talk in a private home," he wrote in the New York Times in May.
"If the situation in China continues to deteriorate, I cannot stand idly by. If I too am arrested, perhaps more Chinese people will awaken to the realities of their situation. My arrest will be my contribution to resisting government efforts to erase the nation's memory."