Security video footage of a police officer involved in a fatal shooting in Heilongjiang province was not tampered with, investigators and prosecutors said on Sunday.

On May 2, police officer Li Lebin shot and killed Xu Chunhe, a 45-year-old man involved in an attack on Li at a railway station.

Although Li has been cleared of wrongdoing by the local police department, edited surveillance video footage, released in a five-minute report broadcast by China Central Television on May 14, prompted questions online.

When the footage showed Li grabbing Xu's wrist at the station, Li's police badge was on his left arm. But later, after Xu followed Li into a room, footage taken by another camera showed the badge was on Li's right arm.

Internet users pointed out that Xu's movements were faster than usual and questioned if some frames of the footage had been deleted.

On Saturday, Xinhua News Agency reported that Liu Yufeng, a technology supervisor at the local railway department, said that one of the station's cameras was accidentally set in "mirror image mode". This meant it recorded a video with a reflected duplication, causing the badge discrepancy.

The report quoted technicians who installed the cameras as saying that they adjusted them to take clear footage and didn't notice that one of them was set in mirror image mode.

Prosecutors said the Digital Data Judicial Expertise Center, a Beijing organization, examined the footage.

On Sunday, the center said the footage provided by the local police had not been edited and the video shown in the CCTV report was not falsified.

Gao Lei, a staff member at the center, said the mirror image was caused by the camera settings.

"Li's use of the gun conformed with the regulations and law," said Sun Chengyi, head of the Harbin Railway Transport Procuratorate.

pengyining@chinadaily.com.cn

(China Daily 05/25/2015 page4)