Federal prosecutors said Thursday Boston Marathon bomber Dzhokhar Tsarnaev does not deserve a new trial in his appeal, arguing, among other issues, that evidence surrounding a 2011 triple murder in Waltham was not relevant to whether he deserved a death sentence. The brief, filed in response to Tsarnaev’s appeal, says in a heavily-redacted section that evidence surrounding the murder, in which his older brother Tamerlan Tsarnaev was a suspect, “had little or no relevance to whether Tsarnaev deserved the death penalty.” Prosecutors say the U.S. District Court appropriately denied Dzhokhar Tsarnaev access to the reports and recordings with Tamerlan’s friend, Ibragim Todashev, who implicated Tamerlan in the murders in an interview with FBI agents before he was shot and killed by one of the agents in 2013. The 431-page brief, signed by William Glaser, U.S. Department of Justice Appellate Section attorney, comes in response to Dzhokhar Tsarnaev’s 1,126-page brief filed in Jan