Authorities said the suspect believed to be responsible for murdering a couple, their two children and their three dogs in their home in Romeoville, Illinois, over the weekend was killed in a fiery car crash Wednesday in Oklahoma.

Nathaniel Huey Jr., 32, of Streamwood, Illinois, was identified Wednesday as the sole suspect in the deaths of Alberto Rolon, 38, Zoraida Bartolomei, 32, and their two sons, ages 7 and 9. Romeoville Police Deputy Chief Chris Burne told reporters at a news conference Wednesday that as police searched for Huey, he was detected in Catoosa, Oklahoma — more than 600 miles from the Chicago suburb.

"The Catoosa, Oklahoma Police Department was alerted to the presence of the suspect's vehicle in their jurisdiction," Burne said. "Acting on this alert, local authorities located the vehicle and attempted to conduct a traffic stop."

A digital license plate scanner spotted Huey’s vehicle, and authorities pursued him. When he attempted to evade them on I-44, he struck another car and crashed his own vehicle into a center barrier, causing it to burst into flames, KJRH reported.

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Nathaniel Huey Jr

Nathaniel Huey Jr., 32, of Streamwood, Illinois, was identified Wednesday as the sole suspect in the deaths of Alberto Rolon, 38, Zoraida Bartolomei, 32, and their two sons, ages 7 and 9. (Facebook)

Burne said a pair of sounds believed to be gunshots were heard from the vehicle.

When reached, Huey was found with a gunshot wound in the driver's seat and pronounced dead at the scene.

A female, who also had a gunshot wound, was located and removed from the passenger side of the vehicle in critical condition, according to Burne. She was transported to the hospital, where she died.

Huey, Cristiana Espinoza

Cristiana Espinoza said her mother, Ermalinda Palomo, 50, was in a relationship with Nathaniel Huey Jr., 32, and was in the car with him at the time of his death. She died later at a hospital. (Facebook)

The Daily Mail identified the woman as Huey's domestic partner, 50-year-old Ermalinda Palomo.

Burne told reporters at a news conference that there had been a relationship between the Romeoville victims and Huey, but did not specify any further. Streamwood, where Huey was from, is located about 35 miles from Romeoville.

The Catoosa Police Department and the Oklahoma State Bureau of Investigation assisted in the police chase.

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Hunter McKee, spokesman for OSBI, said authorities had received two alerts: one for an armed and dangerous suspect and another for a female person of interest in the shootings – later identified as Palomo – who also had been reported missing by a family member.

Catoosa officers initially spotted the suspect’s vehicle, but no one was inside, McKee said. As they were watching the vehicle, two people eventually got in and drove away, which was when police initiated the pursuit.

Oklahoma State Bureau of Investigation vehicle

The Catoosa Police Department and the Oklahoma State Bureau of Investigation assisted in the police chase. (Oklahoma State Bureau of Investigation)

Following the chase, the suspect’s vehicle crashed into a concrete barrier and caught fire.

"We’re still investigating the relationship between the two, and how the man died and how the woman was injured," McKee said.

"Nothing in our investigation to this point leads us to believe that there are any other suspects," Burne added.

He clarified that Huey's death "does not conclude" the "active and evolving investigation." 

The deputy police chief also said that investigators had developed a possible motive for the weekend shootings, but did not provide specifics pending the ongoing investigation.

Who was Nathaniel Huey? 

Burne said Wednesday that Huey was identified as a person of interest in the case "within hours of discovering the victims" on September 17.

According to the Daily Mail, Huey owned a private security firm called Black Bear Security, where he would have had access to "a host of weapons."

Huey standing

Nathaniel Huey Jr., 32, died in a fiery car crash Wednesday in Oklahoma. He was a suspect in a mass shooting in Illinois. (Facebook)

Photos of Huey on his Facebook page show him wearing tactical gear with various weapons, including rifles and sidearms. 

He was described as "irrational and erratic" in a notice circulated by Romeoville police.

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Cristiana Espinoza, 25, who said she was associated with both Huey and Palomo, told The Associated Press that she had filed a missing person's report Tuesday afternoon for Palomo, as she had been concerned for her safety.

"I know she left with him willingly about 4 p.m. Tuesday," Espinoza said, describing him as a "very dangerous man." "When I saw her, she was scared. She was crying. I was in contact with her. We knew where she was. I was begging for her to come home. I honestly feel she left to protect her family."

CBS News reported that Espinoza's mother was the woman found wounded in the car with Huey in Oklahoma, and the three had lived together while Huey and Palmo were in a years-long relationship.

Who is the Rolon-Bartolomei family?

Rolon, Bartolomei, and their two boys were found dead in their home in Romeoville on Sunday evening as police were conducting a well-being check, initiated by a concerned family member. The victims were believed to have been shot between Saturday night and early Sunday.

A photo of the victims' house

Nathaniel Huey Jr., 32, of Streamwood, Illinois, was identified Wednesday as the sole suspect in the deaths of Alberto Rolon, 38, Zoraida Bartolomei, 32, and their two sons, ages 7 and 9 in Romeoville, Illinois. (FOX 32)

Bartolomei’s family members released a statement expressing their gratitude for the support they have received thus far.

"We want to express our heartfelt gratitude for the outpouring of solidarity and support following the tragic loss. At this moment, our primary focus is on channeling support, assistance and love for our family and loved ones," the family said via KJRH. "We appreciate the understanding, and we take this opportunity to once again express our profound gratitude for the solidarity and support extended by people during this period."

A fundraiser in support of the family had raised over $33,000 by Thursday morning.

Police officers standing on sidewalk

Police pulled a "tremendous amount of evidence" from the victims' home in Romeoville, Illinois, amid the ongoing investigation into the quadruple homicide. (FOX 32)

"These were hardworking people that had just bought their first home. Their kids were the sweetest most innocent angels who could hug your worries away," the description of the fundraiser reads. "In just a few hours their lives, their family’s lives completely changed. The world is going to be a much dimmer place without them."

It adds: "Please keep this family in your prayers. Hug your loved ones tight."

Bags outside the home

Romeoville Police Deputy Chief Chris Burne told reporters at a news conference Wednesday that the investigation remains active. (FOX 32)

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Romeoville is located about 30 miles southwest of Chicago.

The Associated Press contributed to this report.