Singh is still rotting in the Lahore jail, where Sarabjit was attacked by other inmates and succumbed to his injuries early today.
It was Kirpal's sister Jagir Kaur, who time and again had raised the issue, but went unheard.
Kaur said, her brother is also lodged in the death cell of Kot Lakhpat Central Jail in Lahore and has spent more than two decades in there.
Kaur had pleaded with the government to take up the issue of her brother's release along with Sarabjit Singh.
Kirpal Singh had crossed the border in 1992 when he was arrested on charges of bomb blasts and spying for India and was sentenced to death.
Later, Pakistan's High Court had acquitted him of charges of bomb blast, but didn't rescind his death sentence in the spying case.