Related Rule
India
Practice Relating to Rule 157. Jurisdiction over War Crimes
India’s Geneva Conventions Act (1960) provides:
When an offence under this chapter [i.e. a grave breach of the 1949 Geneva Conventions] is committed by any person outside India, he may be dealt with in respect of such offence as if it had been committed at any place within India at which he may be found. 
India, Geneva Conventions Act, 1960, Section 4.