According to a Vietnamese soldier who claimed to have been present at the time, Rivière had been brought into Liu Yongfu's presence shortly after the battle ended and had been beheaded on the orders of the Black Flag leader, one of whose close friends had been killed by the French during the battle.
Menurut seorang tentara Vietnam yang menyatakan telah hadir pada saat itu, Rivière telah dibawa ke hadapan Liu Yongfu tak lama setelah pertempuran berakhir dan telah dipenggal atas perintah pemimpin Bendera Hitam, salah satu sahabat dekatnya telah dibunuh oleh Prancis selama pertempuran.