Villain got caught because he was left handed
I'm from India 20 M, and I was watching a Malayalam (South Indian) movie called Memories (2013). In that movie, one of the main reasons the serial killer got caught was that he was left-handed.
This is actually quite common in Indian movies, especially South Indian movies, where a character's left-handedness becomes an important part of the story.
For example, there was another movie whose name I don't remember. The main character was a left-handed woman, and she was suspected of murdering someone. However, the police later realized that she was left-handed. Based on the forensic evidence, they concluded that the murderer must have been right-handed. Because of that, they ruled her out as a suspect and realized that someone else was the murderer.