BENGHAZI, Libya — Libya’s interim government said Monday it will investigate the death of Moammar Gaddafi under international pressure, but authorities remained divided over what to do with the former leader’s decomposing corpse after four days of public viewing. Speaking a day after declaring the country officially “liberated” Sunday from Gaddafi’s four-decade rule, Mustafa Abdel Jalil, head of the Transitional National Council, said the interim governing body has formed a committee to investigate the killing of Gaddafi, who was captured alive Thursday while trying to hide in a drainage pipe east of his final stronghold in Sirte.