U.S. Magistrate Judge Sam Alba signed off on the plea deal, which recommends that Bugman be shuttered for three years, idling its 10 employees, and pay a $3,000 fine. It calls for Nocks to serve six months behind bars and six months of home confinement followed by probation.
Benson can accept these recommendations or impose different punishments, including fines of up to $100,000 for Nocks and $500,000 for Bugman.
"We feel sorry for what happened to the Toone family," Bugman owner Ray Wilson Sr. said after Tuesday's hearing. He added that he hoped the plea deal offers the family some "resolution."
The Toones have filed a wrongful-death suit against Nocks and the company in 2nd District Court. With their case strengthened by the guilty pleas, attorneys for the parties say settlement negotiations are under way, including an undisclosed amount of restitution.
On Feb. 5, 2010, Nocks stuffed Fumitoxin pellets down field mice burrows outside the Toone home. In the following hours and days, fumes seeped into the house. The girls, their older brother, their older sister and their father ended up in the emergency room with severe flulike symptoms.
The two youngest girls died within four days.
In separate plea agreements, Nocks, 64, and the company acknowledged they broke the law by using Fumitoxin in burrows within 15 feet of an occupied structure, putting too many pellets in the burrows and failing to give the Toones a safety data sheet about the dangerous pesticide.
Nocks and Bugman also admitted for the first time Tuesday that they "caused the death of two minor children." The girls' parents, Nathan and Brenda Toone, were in court Tuesday, but did not comment.
U.S. Attorney for Utah David B. Barlow said consumers have a right to expect extermination companies to follow rules and regulations.
"When that trust is broken, we can have the type of tragic outcome that resulted in the prosecution of this case," he said. "We will continue to use all tools at our disposal to aggressively investigate and prosecute those pesticide applicators who, for whatever reason, choose to ignore the safety rules and put lives at risk."
Prosecutors noted that federal law does not allow pesticide violations to be treated as felonies even when someone is killed. However, the law does provide the same penalty as the state crime of negligent homicide.
Lori Hanson, special agent in charge of the Environmental Protection Agency's criminal enforcement program in Utah, noted that the case demonstrates how seriously the agency takes pesticide regulations.
"Warning labels on pesticides are there for a reason," she said. "If not followed carefully, there can be serious, even fatal, consequences."
In the wrongful-death suit, Bugman and Nocks previously denied that Fumitoxin was to blame for the girls' demise. The company said in papers filed June 1 that "other individuals and entities may be at fault for the matters complained of in the plaintiffs' complaint and may have liability for the injuries and damages alleged."
Nocks' defense in that case says "additional investigation and discovery may show the plaintiffs' additional injuries and deaths were proximately cause by the fault of third parties over which Mr. Nocks had no control."
Bugman attorney Dennis James said Tuesday a settlement is in the works.
Toone family attorney Peter Summerill confirmed the negotiations but noted they are not finalized. He added that the Toones will continue their silence on the criminal and civil cases until the cases are concluded.
Bugman and its owner's son, Ray Wilson Jr., face additional federal charges in a separate case that is scheduled for trial next month.
The federal Environmental Protection Agency banned the use of Fumitoxin in residential areas a few weeks after the Toone girls died.
Timeline: Pesticide deaths
Technician Coleman Nocks uses the pesticide Fumitoxin on Feb. 5, 2010, to eradicate field mice at the Toone home in Layton. Both Rebecca, 4, and Rachel, 15 months, breathe the fumes and die within days.
Two months later, the U.S. Environmental Protection Agency tightens the rules for using Fumitoxin to ban its use near homes. Four girls had died from exposure to the pesticide in their homes since the agency originally proposed the ban in 1998. Lobbying by the tobacco industry and the U.S. Farm Bureau Federation had prompted the EPA to drop the proposal.
In August 2010, Bugman agrees to pay $46,800 in fines to the Utah Department of Agriculture and Food in connection with 3,500 violations of state law, including some cases involving the misapplication of Fumitoxin. Originally charged with negligent homicide by Layton prosecutors, Nocks agrees to give up his state pesticide license.
The Toones, determined "to see that those responsible for this tragedy are held fully accountable, both within the criminal and civil justice system," file a wrongful-death lawsuit against Nocks and the company in March 2011. The next month, the Layton criminal charges against Nocks are dropped after he and Bugman are indicted on three misdemeanor counts accusing them of unlawful use of a registered pesticide.
On Tuesday, Nocks and Bugman plead guilty to one count in the two deaths. Sentencing is set for Dec. 20.