ZHANGZHOU, CHINA - DECEMBER 11:   Li Weifu cultivate Vegetables can provide vitamin for Sleuthhound.him training Sleuthhound of English Springer Spaniel search Diluted blood on December 11, 2016 in Zhangzhou,Fujian province, China.  Li Weifu, 60 years old, began to train dogs at the age of nineteen. In 1992, he came to work at the Police Dog Unit of Xiamen Municipal Public Security Bureau. In 2004, he began to concentrate on studying 'the training of Sleuthhound and application technology'. Later on, the Sleuthhound trained by him played a key role in some homicide cases. From 2011, 'the training of Sleuthhound and application technology' began to promote among the national police forces. This technology has helped the nationwide police solve more than 1,500 cases. In 2016, Li Weifu retired with honors, However, his research on Sleuthhound has not stopped, although he doesn't work at the Sleuthhound Unit now, he is training a new generation of Sleuthhound and exploring the limitation of Sleuthhound to blood search.  (Photo by Wang HE/Getty Images)