Gait Recognition Case: Even with different shoes, you can still be identified

On the 9^th day of the first lunar month in 1992, Dong Yanzhen pushed open the door and saw an old man in his fifties squatting next to a bullock cart outside the door. Covered in gray dirt and frost on his face, he was so cold that he could hardly speak clearly. Dong Yanzhen hurriedly pulled him into the house, poured him a glass of hot water, and asked him about the situation.

Note: Dong Yanzhen, a police officer from Fuyu County, Songyuan City, Jilin Province. Born in June 1972 in Nanliangzi Village, Shanjuzi Township, Wengniute Banner, Chifeng City, Inner Mongolia. From a young age, she inherited the skill of shoeprint tracking from her great-grand father. At the age of 16, she began assisting the police in solving cases. Until 2015 she helped solve over 1,500 various criminal cases across the country.

It turned out that the old man was the village chief of Li Jiagou Village, thirty kilometers away. For the past few years, every time it was the first lunar month, the firewood pile in the village would accidentally catch fire, and everyone had to go up the mountain to find firewood to burn. Everyone hated the person responsible for this. Every year, they couldn't find any trace of the culprit. This time, the village's firewood was set on fire again. Because of the strong wind at night, almost all the firewood in the village was burned. After reporting the case, the police station had already cordoned off the crime scene. Everyone specially recommended the old village head to come and ask Dong Yanzhen for help.

Dong Yanzhen arrived at the crime scene, determined the direction of the wind that night, and determined the ignition point. She conducted a trace investigation around the ignition point about ten meters away and finally discovered two suspicious shoeprints. Analyzing the shoeprints, she concluded that the person was male, around 32 years old, approximately 1.74 meters tall, medium build, and had an inward gait. Continuing the investigation, she discovered shoeprints left by the suspect when fleeing, but there were no shoeprints from their arrival. Using shoeprints tracking, Dong Yanzhen and two police officers from the police station followed the intermittent shoeprints left by the suspect for over about 10 kilometers, until the shoeprints led them to a village called Wangjiaao. Dong Yanzhen asked the village chief about the exits of the village and finally found the suspect's shoeprints about one kilometer outside the village, circled the shoeprints outside the village and then returned to Li Jiagou Village from another path. Dong Yanzhen chased the suspect from morning until evening, covering a round trip of over 20 kilometers. When she returned to Li Jiagou Village, her ears were frozen, her eyelids and face were swollen, tears were streaming down her face. She looked exhausted. The villagers were deeply moved by her hard work.

The next morning, she asked the village chief of Wangjiaao Village to gather all the men aged 20-40 in the village and clear a space outside. Each person walked back and forth twice to identify the shoeprints. The investigation continued for three days, involving a total of 165 people, but none of them matched the characteristics of the suspect's shoeprints. Some police officers at the police station began to doubt Dong Yanzhen's ability to find the suspect through gait and shoeprints analysis. To test her, two police officers created a fake crime scene, made two sets of shoeprints, and asked her to identify them. Dong Yanzhen correctly identified the age, height, and gait characteristics of the two individuals, pointing out that the shoeprints belonged to those two police officers. The two police officers gave her a thumbs up, admiring her abilities.

At that moment, a young man rode up on a motorcycle. When the young man got off the motorcycle and walked towards them, Dong Yanzhen immediately pointed out that it was this young man who started the fire. The police called the young man over, and when he left a pair of shoeprints, it was discovered that he was wearing a pair of cotton shoes, while the shoeprints found at the scene were from hiking shoes,which didn't match. Dong Yanzhen asked the young man to walk back and fortht wice, confirming that it was indeed him. The young man initially denied it.Dong Yanzhen said, "Even though you changed your shoes, you can't change your feet. Your gait characteristics, the wear patterns on your shoes, and the shoeprints left at the scene all match." After careful investigation and evidence collection, the young man finally admitted to starting the fire. His name was Li Er, 31 years old, 1.73 meters tall, weighing 71 kilograms, with abow-legged gait. He had harbored grievances against the village chief for many years. After committing the crime, he had taken his wife to her parents' house and had just returned to see what was happening. He thought changing his shoes would keep him safe, but little did he know that Dong Yanzhen was on the case.

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