A 28-year-old Bangladeshi, one of the main accused in the sexual assault of a septuagenarian nun at a Ranaghat convent school, has been arrested from Sealdah railway station here. Nazrul aka <g data-gr-id="12">Nazu</g> was arrested from Sealdah station while he was getting down from a local train late last evening, SS CID Chittaranjan Nag said on Thursday.