Younus, the brother-in-law of Asia Bibi, a Pakistani Christian who had spent years in prison before her acquittal, was killed on Monday in the city of Sheikhupura in the Pakistani province of Punjab.
According to the FIR, Younus went to his farms on May 24 and did not return home at night. His body with a slit in his throat was found on the farm the next morning.
In 2011, Salman Taseer, the influential governor of Punjab, was murdered after making headlines by asking forgiveness from Asia Bibi, who had been sentenced to death for allegedly insulting Prophet Muhammad.
A month after Taseer's death, Minister of Religious Minorities, Shahbaz Bhatti, a Christian who spoke out against the law, was shot in Islamabad, underlining the threat from law critics.
Asia Bibi is now in exile after the Supreme Court of Pakistan acquitted her in October 2018 due to insufficient evidence.
Asia Bibi reported the hellish conditions of eight years on death row for blasphemy, but also the pain of exile, and recently broke her silence to give her first personal look at an ordeal that caused international outrage.
French journalist Anne-Isabelle Tollet, who wrote a book about her, once lived in the country where she led a support campaign for her.
"You already know my story through the media," she said in the book. "But you are far from understanding my daily life in prison or my new life," she said.
"I became a prisoner of fanaticism," she said. In prison "tears were the only companions in the cell".
Pakistan's blasphemy laws include a potential death sentence for anyone who offends Islam. Critics say they have been used to persecute minorities and to unfairly attack minorities.
No Pakistani government has made changes to the blasphemy law out of fear of a backlash.