Attornies Carlo Dalla Vedova and Luca Maori said Saturday they had sent letters to Lifetime warning they would go to US court to try to sequester the film if it isn’t canceled and a trailer removed from Lifetime’s website. “Amanda Knox: Murder on Trial in Italy,” which features “Heroes” star Hayden Panettiere in the title role, is due to air Feb. 21. Les Eisner, a spokesman for Lifetime’s parent company, A and E Television Networks, said the network was not commenting at this time. Knox and ex-boyfriend Raffaele Sollecito were convicted in 2009 of sexually assaulting and murdering Meredith Kercher in the apartment she shared with Knox in the central Italian city of Perugia. Kercher was stabbed to death the night of Nov. 1, 2007. Knox was sentenced to 26 years in prison; Sollecito 25 years. The film is based on the trial. A preview posted to Lifetime’s website shows scenes from the runup to the murder — including one split-second scene showing the actress playing Kercher, wearing a gray bra, being attacked by two men.