The man suspected of killing a suburban Chicago family — including two young kids and their three dogs — was a gun-toting security guard whose stepdaughter called him a “very dangerous man.”

Nathaniel Huey Jr. — who appears to have killed himself in a blazing car to evade capture for the shocking slaughter — owned a private security firm called Black Bear Security.

The 32-year-old suspect was pictured on Black Bear Security’s Facebook page with guns, ammunition and body armor, with one post reading: “I can and I will.”

One photo even showed him holding an assault rifle with what appeared to be a suppressor.

Huey and his partner, Ermalinda Palomo, 50, were identified as “persons of interest” in the murders of Zoraida Barolomei, 38, her husband, Alberto Rolon, 32, and their children, Adriel, 10, and Diego, 7, who were all found shot to death Sunday in their home in Romeoville, Illinois, a suburb of Chicago.

Cops have not clarified what Huey’s motive may have been in the gruesome killing, only revealing that there was a “nexus between our suspects and the victims as well as possible motives” and a “tremendous amount of physical evidence.”

An investigative bulletin circulated by the Romeoville police after Huey and Palomo fled also described him as “irrational and erratic” with extensive firearms training.

Palomo’s daughter, Cristiana Espinoza, called Huey a “very dangerous man.”

“He’s a huge manipulator, a huge manipulator,” she told NBC News.

She said that when Huey first started dating her mother about eight years ago, she thought “he wasn’t too bad of a guy.”

But a few months ago, she said, “something switched.

“He was shutting all of us out, including my mom, and now this,” Espinoza said. “He started becoming suspicious … keeping to himself, staying in the garage, pushing us all away — even my mom.”

It is believed Huey and Palomo were married, with Huey referring to her as his wife on Facebook.

Following the Chicago-area murders over the weekend, Palomo’s family filed a missing person’s report for her as she and Huey remained on the run.

It said she was last seen on Sept. 19, and was filed after the family received a worrying text from Palomo, which read “Take care of my grandbabies,” family attorney John Paul Ivec told ABC Chicago.

He described Palomo as a victim of Huey, just like the suburban Chicago family.

The search ultimately came to an end on Wednesday in Catoosa, Oklahoma — about 650 miles from the victims’ home.

Authorities were tipped off by a digital license plate reader that positively identified Huey’s vehicle, prompting police there to conduct a traffic stop.

But Huey “immediately attempted to elude the officers,” Romeoville police said, causing him to crash in a fiery blaze.

As officers approached the car, they heard two gunshots and found both wounded.

Huey was pronounced dead at the scene, while Palomo was rushed to a nearby hospital in critical condition.

Police said there is no reason to believe there are other suspects, as family and friends continue to question why Huey may have wanted them dead.

Friends described the Barolomeis as “hardworking people that had just bought their first home” in a GoFundMe created to cover funeral expenses.

“Their kids were the sweetest, most innocent angels who could hug your worries away,” it 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.”