The state Justice Department has asked a federal appeals court to keep Brendan Dassey in prison, while it continues a court battle to keep his murder conviction in place. Both a federal magistrate and a panel of three appellate judges say Dassey’s conviction should be overturned because sheriff’s officers coerced him into confessing that both he and his uncle Steven Avery brutally killed Teresa Halbach at the Avery family’s auto salvage yard in Manitowoc County in 2005. Dassey was 16 at the time, and the 2015 Netflix series “Making a Murderer” pointed to various flaws in the process of convicting both Dassey and Avery, who is also appealing his guilty verdict in the wake of that series. Dassey’s lawyers asked the federal appeals court in Chicago for an immediate release of their client. But the state said Monday that Dassey should stay behind bars while an appeal continues, and the Justice Department said that a jury found Dassey guilty.