Police conduct a death investigation after a man and a woman, who were co-workers, were found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Photo: Tracy Mathesius

The coroner ruled that a 20-year-old Crystal Lake woman and a Grayslake man died from carbon monoxide poisoning after the two co-workers were found dead in a parked car in Crystal Lake.

The Crystal Lake Fire Rescue Department and Crystal Lake Police Department responded around 5:32 a.m. on November 4 to the 700 block of Coventry Lane for a medical call.

Crystal Lake Deputy Police Chief Richard Neumann said a 911 caller reported two people possibly asleep in a vehicle parked on the roadway.

Police conduct a death investigation after a man and a woman, who were co-workers, were found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Photo: Tracy Mathesius

Police officers arrived and reported finding a male and a female in a vehicle. Both were unconscious and not breathing.

McHenry County Coroner Dr. Michael Rein identified them as Yeisimar Morales-Sanchez, 20, of Crystal Lake, and Kirby Graham, 32, of Grayslake.

Neumann said Morales-Sanchez and Graham showed “no obvious signs of injury.”

Police conduct a death investigation after a man and a woman, who were co-workers, were found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Photo: Tracy Mathesius

Two ambulances and two fire engines were dispatched to the scene and officers began performing CPR on the victims.

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Paramedics arrived and confirmed Morales-Sanchez and Graham were still unresponsive as they took over lifesaving measures.

Lifesaving measures were unsuccessful and both were pronounced dead at the scene, Neumann said.

Police conduct a death investigation after a man and a woman, who were co-workers, were found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Photo: Tracy Mathesius

A heavy police presence was reported at the scene throughout the morning.

Officers set up crime scene tape around the scene as they worked to investigate the incident.

The car involved was parked on South Coventry Court near Coventry Lane.

Kirby Graham, 32, of Grayslake, was found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Provided Photo

Morales-Sanchez and Graham were both co-workers who worked at a manufacturing plant in McHenry, the coroner’s office said.

Neumann previously said earlier this month that investigators were still gathering evidence but were “confident” there was no danger to the public as a result of the incident.

The coroner’s office initially said earlier this month that autopsies were performed on Morales-Sanchez and Graham on November 6 but the investigation remained pending toxicology testing.

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Police conduct a death investigation after a man and a woman, who were co-workers, were found unresponsive in a parked car before being pronounced dead in the area of South Coventry Court and Coventry Lane in Crystal Lake on November 4. | Photo: Tracy Mathesius

Rein announced on Wednesday that the investigation had been completed and it was determined that Morales-Sanchez and Graham both died as a result of carbon monoxide toxicity.

The car that the two were inside, which was driven by Graham, had a defective exhaust system, Rein said.

The coroner’s office said they worked collaboratively with the Crystal Lake Police Department and Crystal Lake Fire Rescue Department and found the deaths were accidental.

A wake and funeral service for Graham is scheduled from 10 a.m. to 12 p.m. on Saturday at Faith Temple Church of God in Christ in Evanston. No funeral services were publicly announced for Morales-Sanchez.