When was St. Thomas martyred in India?

It is doubtful whether Saint Thomas ever went to India, although local tradition says that the Apostle Thomas came by sea from Arabia and landed on the Malabar coast. Alternatively, he came overland, down from the north. One tradition is that he left India for the last time circa 69 CE, leaving behind a strong, self-propagating and self-sustaining community. Another tradition is that Thomas was martyred at Chennai in India, probably about 73 CE. Whatever the historicity of such indigenous traditions, there can be no question as to their great antiquity or to their great appeal in popular imagination.

A Syrian tradition is that Thomas died a martyr in Edessa, Syria. Every early Christian community wanted its own martyr, and preferably one of the apostles - thus some apostles died multiple deaths in multiple locations.