The alleged murderer of Sikh rights activist and inter-faith harmony advocate Charanjit Singh was arrested by the Counter-Terrorism Department (CTD) on Thursday.Charanjit was killed on May 29 when a lone gunman barged into his grocery store and shot him.A statement by the CTD claimed that an operation was conducted in the Ghalla Mandi area of Peshawar and the alleged killer, identified as Sheheryar Sultan, was arrested.An investigation officer confirmed to The Express Tribune that the activist was killed for failing to pay extortion.“The suspect is part of a criminal group involved in extortion,” he said adding that they team has also found evidence of Charanjit previously paying extortion money.Singh lived a very public second life and was a scholar and activist promoting interfaith harmony.Singh had migrated to the provincial capital in the early 1970’s for business and hailed from the Sadda region of Kurram district.Charanjit lived in Mohalla Bar, inside the walled city and ran his store on Scheme Chowk together with his brother. Two of his other brothers are traditional physicians.