A Colorado man who admitted fatally shooting his wife pleaded not guilty last week to murder after saying the first gun shot was an accident, and the second gunshot was a "mercy killing."

According to The Gazette, 46-year-old Black Forest resident Kenneth Lankford entered a plea of not guilty on Thursday to the first degree murder of his wife, 51-year-old Terry Lankford. Kenneth Lankford said that he was also not guilty of murdering 51-year-old Carol Fowler, and wounding her husband, 52-year-old Thomas Fowler.

The Colorado Springs Gazette reported last month that Kenneth Lankford had told deputies that he was forced to shoot and kill his wife because she had been injured when he accidentally shot her during an argument.

"He said he didn't mean to shoot his wife, and he didn't mean to hurt the man, but that the woman's death was definitely a murder," Sheriff's Sgt. Greg White explained at a preliminary hearing in May.

White said that Kenneth Lankford told them that he had gotten in an argument with his wife when the couple heard a knock at the door, and were concerned because he had had been in trouble with the law before. The couple retreated to a bedroom, where Kenneth Lankford said that Terry Lankford reached for his gun, and was accidentally shot.

"[Lankford] said Terry was making the most 'God-awful gurgling sound,' and he felt horrible, so he held the gun with both hands and shot her to put her out of her misery," White recalled.

Kenneth Lankford told deputies that he then lashed out at the couple who had knocked on his door, shooting Thomas Fowler in the face. Carol Fowler died after being shot in the chest, collarbone and back of the head.

Deputies testified that Lankford told them that he had been using meth the night before the killings.