Chad Doerman, an Ohio father accused of murdering his three sons, had been plotting the killings for months, according to court documents. “The defendant gave a statement during an audio and video recorded interview, during which he admitted to having been thinking about shooting his sons since October,” said the bill of particulars which was obtained by WCPO. Mr Doerman hadn’t slept in the three or four days leading up to the murders because “the thoughts of having to kill his sons was so heavy on him,” it added. The document sets out the series of events that led up to when the father allegedly killed his sons aged three, four and seven. After Mr Doerman came home from work early, he asked his wife and the three boys to join him for a nap in the master bedroom, the bill states. While the rest of the family were situated in the master bedroom, Mr Doerman’s 12-year-old stepdaughter was watching television in the family room. That room housed a Marlin Model HC .22 rifle, WCPO reported. As his family lay down to nap, Mr Doerman removed the rifle from its safe and began loading a magazine into it, the outlet said, before shooting one of his sons twice. His wife reportedly tried to help the child while yelling for her other boys to run. The 12-year-old moved to the master bedroom in time to witness the first shots fired, according to the document. She ran after one of her brothers, yelling for him to run away, but Mr Doerman shot the boy as he ran, causing him to fall, and allowing his father to shoot him again at close range, the outlet wrote. The 12-year-old then picked up another of her brothers and carried him out of the house, the document continues. But Mr Doerman caught up to the pair as they approached the road. He raised his weapon and told his stepdaughter to put her brother down, it said. Apparently out of ammunition, Mr Doerman tried to fire again but it the gun didn’t work, allowing the boy to run to his mother, who was trying to help her son who had been shot outside. The step-daughter ran toward the local fire department, telling a passerby who stopped her that “her father was killing everyone.” Mr Doerman then went up to his wife and the third boy. He bit his wife to try to get to his son, the document says. As they fought, Mrs Doerman was able to grab hold of the rifle but her husband fired, shooting her through her thumb. This caused her to drop the third boy, who Mr Doerman allegedly then shot in the head. “After the defendant executed all three boys, he sat on the side stoop of the residence” and watched his wife try to save her children, the outlet reported. The document says that the father fired nine shots: one boy was shot once, the other two were each shot four times. According to the sheriff’s office, Mr Doerman faces 21 counts: 9 counts of aggravated murder, 8 counts of kidnapping, and 4 counts of felonious assault. His first court appearance was on June 16, one day after the killings. Mr Doerman pleaded not guilty; the judge ordered his bond to be set for $20 million. “This is the most serious offense that we have on the books, judge,” said David Gast, assistant Clermont County prosecutor, during the first court appearance. “This is it. You can’t commit a more serious offense.” Clermont County Prosecutor Mark Tekulve announced in June that his office plans to seek the death penalty for Mr Doerman. “My goal is to have this man executed for slaughtering these three young boys,” Mr Tekulve said. “It is an incomprehensible act of horror that he perpetuated on this family.” Read More Ohio father accused of killing his 3 young sons indicted on murder charges Heartbreaking 911 calls reveal mother’s panic after husband ‘executed’ three young sons Father of man who executed his three young sons shares disbelief: ‘He just snapped’