A Pakistani lawyer known for pursuing cases of those unlawfully detained by the country’s security agencies was abducted overnight from his home in the garrison city of Rawalpindi, his son said Tuesday.

According to the son, several armed men in plainclothes knocked on the gate of the family’s home on Monday night. When the family opened the door, the men barged in and snatched his father, Inamur Rehman, shoved him into a car and then sped away.

Rehman, a lawyer and a retired military officer, was never a threat to anyone, said the son, Husnain Inam. He refused to speculate on who was behind the abduction.

“We are still in a state of shock,” said Inam, adding that the family was too terrified to cry out for help during the abduction.

Inam, a college teacher, said he’s formally reporting the abduction to the police. No government official could immediately be reached to comment.

Rehman has been vocal critic of Pakistani security agencies and has also represented several people detained by the country’s military-backed spy agency in recent years. He has previously reported being harassed by security agencies.

In 2012, he petitioned a court challenging the government’s move to keep outgoing army chief Gen. Ashfaq Parvez Kayani in office for another three years.

Last Tuesday, dozens rallied in the capital, Islamabad, marking the the International Human Rights Day by urging the government to release hundreds of people who they say have been “forcibly disappeared” by security agencies in recent years.

The government has repeatedly denied the allegations. Although Pakistani law prohibits detentions without court approval, officials privately concede that intelligence agencies are holding an unspecified number of suspects. The officials say the detentions are because of ties to militant groups.