The motive was to teach his parents a lesson as they had arranged his younger brother's marriage, instead of his.
An Indian court sentenced him to life imprisonment for the murder and he was acquitted in 2011. When he reached home, his parents chained him after he attacked them. Later, they again got him locked up.
Three days ago, he was released from the lock-up and went to the graves of his maternal grandparents at Wali Faqir in India.
He then sneaked across the border to visit the graves of his paternal grandparents near Gogasar in Pakistan to seek forgiveness for murdering his sister, the report said.
Replying to a farmer's question on why he trespassed into Pakistan just to visit a graveyard and why he had not obtained a visa, Abu Bakar said he had no means to get a passport or a visa.
He further told farmers that he was injured when he scaled barbed wires at the frontier and fractured his leg while leaping from a height of 15 feet.
Officials of the Pakistan Rangers said Abu Bakar was being questioned by intelligence agencies.
