Chandigarh, January 6: Five years after being discharged in a murder case that had kept him on the run for 31 years, Ajmer Singh, a 58-year-old political activist, was in for a rude shock when he was picked up on the same charges by UT Police on Thursday night. He was let off after 19 hours in custody.

Singh, who remained underground for almost all his youth after charges of association with Naxalite associates who allegedly killed a police constable and injured another to set him free, surfaced in 2001 when the murder charges were dropped. He maintained a high profile thereafter, and even wrote a book on 20th century politics, which was released at a public function.

Recalling the Thursday night terror, Singh said Sub Inspector Amanjot Singh of the Crime Branch arrived at his house around 9 on Thursday night, armed with a box of sweets and an invite. But before he could figure out the invite, Ajmer said four more persons slipped in quietly and told him that he was being arrested for involvement in a car accident. ‘‘All of them were in plain clothes and I was not shown any search or arrest warrants,’’ he said.

By the time he reached the police station, Singh said the cops had ransacked his room and picked up “each and every scrap of paper. My first book was against the state, and it seems they were interested in finding out more about my writings.”

Singh said officials at the police station told him that he had been arrested on account of a murder case dating back to December 1970. ‘‘When they finally took me to court, they were pulled up and told that if no case was made out they should release me.’’

Singh said after 19 hours in custody, the police returned three suitcases laden with his material, mostly books and almost 1,000 folios of hand-written material, part of his next book on post-Bluestar Punjab.

To hit the rewind button, Ajmer Singh, then named Gobinder, was a third-year student of electrical engineering at Guru Nanak Engineering College, Ludhiana, when the police arrested him for possessing Naxalite literature.

While he was being brought back from his interrogation centre, his associates attacked the police party, killed one constable and injured another, and set him free. For the next three decades, he remained on the run till his discharge by the Kapurthala police in 2001.