Officials in Illinois have already identified the father and daughter killed last week in what investigators described as a murder-suicide.

On Thursday afternoon, nine-year-old Adrianna Anderson and her 36-year-old father, Christopher Anderson, were found dead inside his Lake Villa house.

According to a People report, Adrianna's mother called the police and asked them if they could check on her daughter after school officials informed her that Adrianna never showed up for school.

"Lake Villa Police Officers entered the home and found [Adrianna] deceased and the girl's father, a 36-year-old man, deceased," the investigators' statement said.

The statement further noted that Adrianna's parents shared custody of her but lived in separate residences. Police said Adrianna's mother agreed to allow the girl to stay with her father overnight on Wednesday. Police added that the mother tried to call the father when the girl failed to show up in school.

"After several attempts of not being able to reach the father, the mother called Lake Villa Police to conduct a well-being check," the police statement read. 

Related story: Psychologist Mom Killed Twin Daughters Before Committing Suicide

Police Investigation on Adrianna Anderson's Death

Police said they are investigating the deaths as a murder-suicide and believe that the father killed Adrianna Anderson before taking his own life. According to a Patch report, investigators have yet to determine the motive and continue to talk with family members.

Lake Villa Police Chief Crag Somerville said the case is a tragic set of circumstances and offered their deepest condolences to the child's family.

Somerville reassured the Lake Villa community that there is no evidence to suggest that there is a threat to the public. The incident is still under investigation by members of the Lake County Major Crime Task Force with the Lake Villa Police Department.

Lake County Major Crimes Task Force Spokesman Christopher Covelli said the girl and the father both died as a result of "sharp-force injuries." Meanwhile, complete autopsies on the father and the daughter were still pending, according to a Daily Mail report.

U.S. Murder-Suicide Rates

More than 1,300 people died in murder-suicides in America in 2017, and 91 percent of the killers used a gun, according to a Violence Policy Center (VPC) report in 2018.

The study further noted that there were 296 murder-suicide events during a six-month period. It also equals to more than 11 murder-suicides per week. These events caused 633 deaths, of which 296 were suicides, and 367 were homicides.

VPC Legislative Director Kristen Rand said that murder-suicides occur daily across the country, which claimed the lives of spouses, intimate partners, children, and co-workers.

"The disturbing findings in our study make clear the need for a comprehensive national data collection system that measures the full extent of murder-suicide in our country," Rand said in a statement.

The study's estimate for the total number of murder-suicides per year is consistent with the standard range of medical studies' estimates.

It also relied on news reports for its analysis as there is no comprehensive national database on murder-suicides in the U.S.

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