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An Illinois man who suspected that his girlfriend had contracted COVID-19, the disease caused by the coronavirus, shot and killed her and then himself, authorities said.

Both tested negative for the disease.

At about 8 p.m. Thursday, Will County sheriff's deputies went to a home in Lockport Township, about 30 miles southwest of Chicago, to conduct a welfare check.

All of the doors and windows were locked from the inside, according to the sheriff's office. Deputies and fire personnel forced their way into the home.

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Patrick Jesernik, 54, and Cheryl Schriefer, 59, were found dead in separate rooms with obvious signs of trauma to their heads, the sheriff's office said in a statement. The couple, who were not married, had been together for eight years, according to Cathy Hoffmeyer, a spokeswoman for the sheriff's office.

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A revolver containing two spent shell casings and three live rounds was found near Jesernik's body, the sheriff's office said. There were no signs of a struggle, and the home was neat and orderly.

A man at the scene told deputies that Jesernik's parents asked him to check on their son because they had not heard from him.

"A check of the address was conducted by detectives which showed no previous calls for service in regards to domestic disputes," the sheriff's office statement said. "A check of both deceased individuals was also conducted which showed very limited police contact."

Family members later arrived and told authorities that Jesernik had been scared that he and Schriefer had contracted COVID-19, saying Schriefer had been tested two days earlier, the sheriff's office said. The relatives said that Schriefer had been having a hard time breathing and that, to their knowledge, she had not gotten her test results.

Autopsies Friday determined that both died from single gunshot wounds to the head, the sheriff's office said. Schriefer's death was ruled a homicide. Jesernik died from a self-inflicted gunshot wound, and his death was ruled a suicide, according to the sheriff's office. Both tested negative for the virus.

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The sheriff's office said that during the COVID-19 pandemic, the vast majority of service calls deputies have been responding to involve domestic disputes and crisis intervention.

"As a reminder, if anyone is a victim of a domestic violence situation, the Will County Courthouse remains open for individuals in need of obtaining an order of protection," the sheriff's office said.

The Will County Courthouse is open Monday thru Friday from 8:30 a.m. to 3:30 p.m. and Saturdays from 8:30 a.m. to noon to issue orders of protection.

If you or someone you know is in crisis, call the National Suicide Prevention Lifeline at 800-273-8255, text HOME to 741741 or visit SpeakingOfSuicide.com/resources for additional resources.