WEBSTER CITY, Iowa – Closing arguments began Monday in the trial of a man accused of killing an Iowa State Trooper. Michael Lang faces first degree murder charges for the shooting death of Sergeant Jim Smith in Grundy Center last year. Sergeant Smith was a 27-year veteran of the force. Police said Lang led officers on a chase, assaulted an officer who pulled him over, then barricaded himself inside his home. Officers then entered when Lang refused to surrender. And that’s when investigators say Lang shot Smith, killing him. On Thursday last week, Lang’s lawyers chose not to call a single witness to the stand. Lang also did not testify at his trial. Prosecutors called 16 witnesses before resting their case at the Hamilton County Courthouse in Webster City.