Kirigiri is so smart.
How can a detective never leave an armchair yet solve so many crimes.
I have a feeling he may be a person who has played a role in the Duel Noirs or could even be one of the members of the Committee, and could already know the answers to the crime as he could have been a Backer to the Funds anonymously and watching the camera footage of the crime he would know exactly what happened and be able to solve the case!