NEWBURYPORT – “Killer Poet,” a film about the life of convicted killer Norman Porter Jr., won the best feature-length documentary award at the 5th annual Newburyport Film Festival.The award was presented Sunday to producer/director Susan Gray of Rowley, co-producer Dominic Musacchio, editor Andrew Kukura, and to Bestor Cram and his Boston-based company, Northern Light Productions.Porter’s story is well known on the North Shore and his capture after more than 20 years on the lam made national headlines in 2005. The film details the deadly robbery at the former Robert Hall clothing store in Saugus on Sept. 29, 1960, in which store clerk John “Jackie” Pigott of Lynn was killed by a shotgun blast.Pigott came from a prominent Lynn family. His father was vice president of Essex Trust in the city’s Central Square, his mother an executive secretary at GE. The young man was engaged to Claire Wilcox, a teller at the Lynn bank.Porter, who grew up in Woburn and a series of reform schools, and his partner in crime, Theodore Mavor of Peabody, were quickly caught and convicted. Mavor was eventually stabbed to death in prison. Porter, who denied shooting Pigott, later escaped from a Cambridge courthouse. His accomplice in that incident shot a jail guard to death as they fled. Porter’s freedom didn’t last long.While serving two life sentences, Porter literally walked away from a minimum-security prison in 1985. He was eventually caught in Chicago in 2005, living under the alias J.J. Jameson.Gray and the production crew interviewed Porter in prison as well as the State Police detectives responsible for his capture, and a wide array of prison officials, journalists, friends, acquaintances and the families of the victims. Many of the scenes in the film are from downtown Lynn in the 1960s.Dottie Johnson, a former Lynn resident and cousin of Pigott’s who led the public effort to keep Porter from being paroled, reminded the film festival audience that Monday marks the 48th anniversary of the murder of her kin. “We still miss Jackie,” she said.