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Belleville News-Democrat, Derik Holtmann, Associated Press
Angela DeCiccio, center, mother of murder victim Sheri Coleman is escorted by her son and Sheri's brother, Mario Weiss, right, and Sheri's cousin, Enrico Mirabelli, into the Monroe County Courthouse in Waterloo, Ill., for opening statements on the first day of the murder trial of Christopher Coleman. Coleman is charged with strangling his wife, Sheri, and two young sons in May 2009 in their Columbia, Ill., home.

WATERLOO, Ill. — The defense attorney for an Illinois man accused of killing his wife and two sons disputed accusations from prosecutors the former Marine spent months setting up the crime.

Defense attorney Bill Margulis said Monday at the opening of Christopher Coleman's trial that the 34-year-old experienced "common" marital problems. A pathologist testified the victims died of ligature strangulation.

Prosecutors claim Coleman killed his family because he feared his affair with his wife's longtime friend would cost him his $100,000-a-year job.

Monroe County State's Attorney Kris Reitz (ryts) says the case will be complicated for jurors. Reitz contends evidence will show Coleman lied when he insisted he was at the gym when his family was strangled in their Columbia home in May 2009.

Coleman pleaded not guilty and remains jailed without bond.