A jury found David Hosier guilty of a Jefferson City double murder.
Both sides wrapped up their arguments in court Wednesday and handed the case to the jury around 3:30 p.m. The trial, which was supposed to take up to two weeks, lasted only three days.
Just before 5 p.m., a jury found Hosier guilty on all four counts.
The defense only called two witnesses to testify and Hosier did not take the stand.
Hosier was charged with first-degree murder, first-degree burglary, armed criminal action and unlawful possession of a firearm in shooting deaths of 61-year-old Rodney Gilpin and his wife, 45-year-old Angela Gilpin, in Jefferson City in September 2009.
A jury was selected last week in St. Charles County. The trial has been delayed twice because not enough potential jurors could be found in Cass and Clay counties.
Hosier and Angela Gilpin had an affair but she was trying to reconcile with her husband when the couple was found shot to death at her apartment in September 2009.
Hosier was charged in both killings, and the jury heard testimony about both. But the judge clarified Wednesday that this week's trial was only for Angela's death. The status of the case in Ronald's death is unclear.