From Shanghai 1937: Stalingrad on the Yangtze, by Peter Harmsen (Casemate, 2015), Kindle Loc. 2993-3008:
The maltreatment of prisoners was mutual. Accounts of Japanese prisoners being kept for long by the Chinese were virtually non-existent. Frequently, this was due to circumstances at the front, whether in the urban areas or the surrounding countryside. Under confusing and dangerous battlefield conditions, there was simply nowhere to place captives. Officers saved themselves endless trouble by simply ordering prisoners killed. However, even when facilities were available, nothing was done to accommodate enemy POWs. Dutchman de Fremery never saw or heard about a single instance of any Japanese troops being among the 20,000 injured soldiers being treated at Chinese hospitals in the Shanghai area.
Especially at the start of the Sino-Japanese war, the treatment of Japanese prisoners at the hands of the Chinese “beggared belief” and marked a throw-back to a less-civilized past, according to the German war correspondent Lily Abegg. Often civilians took part in the maltreatment of captured Japanese. Abegg mentioned an example of two Japanese pilots who were shot down during a raid of Nanjing. They were “torn to pieces” by a furious mob, and when military police arrived they could not find a single trace of them remaining on the scene.
The killing of Japanese prisoners, often in a horrific fashion, was a source of concern for the Chinese command. It wanted to be able to show off well-treated prisoners for propaganda purposes, and doubtless, it also wanted to exploit the captives for their intelligence value. In the end, it offered a money prize for any Chinese, soldier or civilian, who was able to hand over a living Japanese prisoner to the authorities. However, this had little effect. “The soldier’s hatred toward the Japanese,” a Chinese general said a little later in the war, “is enormous. It’s impossible to have a prisoner delivered to headquarters although we pay from 50 to 100 yuan upon delivery, and there are severe punishments for not doing so. The soldiers say that the prisoners die along the way.”