A Dubuque man who is accused of killing his wife and trying to make it look like a suicide has pleaded not guilty to a murder charge. 34-year-old Brett Zartman is charged with first-degree murder in the death of 32-year-old wife Carol. Carol Zartman’s body was found in the family’s mini-van in the closed garage, with the van running. However an autopsy determine she died of suffocation. Brett Zartman submitted a written not-guilty plea, and is scheduled to appear in court Monday. He’s being held on a 750-thousand dollar bond.