The family of four people who died in a fiery crash involving a tractor-trailer in Henry County last month has filed a lawsuit against multiple companies and drivers.

Attorney Terry Jackson told Channel 2 Action News that security footage from a Legacy Ford dealership near I-75 and Ga. 20/Ga. 81 is crucial evidence in learning what caused the fatal wreck on May 16.

The video appears to show a tractor-trailer, which was driven by 39-year-old Mohabe Nybil McCoy, not slow down before plowing into a trailer being hauled by a pickup truck, killing the four people inside, AJC.com previously reported.

A security camera at Legacy Ford/Hyundai of McDonough captured this footage of a fatal collision Thursday on I-75 north of Hwy 155 outside McDonough. The dealership is owned by a Georgia lawmaker, Sen. Emanuel Jones, D-Decatur, who shared the video. Two people died in the crash.

Graciela Sanchez told Channel 2 the four people killed were her family members.

The deceased included her cousins Jaime Sanchez, 26 and Fermin Sanchez, 20, as well as her godfather Jose Ibarra Yanez, 42, and his girlfriend Juana Adaliris Ortiz-Martinez, 31. All of the victims were from Dublin in Middle Georgia.

RELATED: 4 dead after fiery tractor-trailer crash on I-75 in Henry County

Left to right: Fermin Sanchez, Jaime Sanchez, Jose Ibarra Yanez and Juana Adaliris Ortiz-Martinez.

Credit: Channel 2 Action News

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Credit: Channel 2 Action News

“For the family to know what happened ... to see that video — devastating,” she told the news station. “(We) couldn’t believe it.”

The video was included in the electronic version of the lawsuit filed by Jackson on behalf of Fermin and Jaime’s families in Gwinnett County, Channel 2 reported. The suit was filed against a group of trucking industry businesses, insurance companies and four drivers, including McCoy.

“You can see our clients come slow, and then you can see the tractor-trailer,” Jackson said. “There’s no braking — violent collision.”

Terry Jackson

Credit: Channel 2 Action News

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Credit: Channel 2 Action News

The other drivers were involved in a crash farther ahead on I-75 North, which caused backups for more than 12 miles, Channel 2 reported. One of those drivers is accused of causing that crash, which also involved a tractor-trailer, and the other two drove vehicles that had allegedly stopped on the interstate to avoid a blown out tire.

Jackson told the news station the wreck caused a tractor-trailer ahead of the pickup to slow, which is why his clients began braking. The tractor-trailer driven by McCoy didn’t, however, causing the pickup truck to be crushed between the two tractor-trailers before catching on fire, Jackson said.

MORE: Truck driver charged in deaths of 4 killed in fiery crash on I-75

Mohabe Nybil McCoy

Credit: Henry County Sheriff's Office

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Credit: Henry County Sheriff's Office

A witness reportedly told Jackson that McCoy may have been asleep before the impact.

“She looked in the tractor and saw that he had his head down and wasn’t paying attention,” Jackson said.

McCoy is facing misdemeanor charges, including second-degree homicide by vehicle, improper turn and driving too fast for conditions. He has not responded to Channel 2’s request for comment.

He was arrested and released on a $10,000 bond.

In other news:

According to the Marietta Police Department, 51-year-old Michael Beltran tried to kidnap the boy at Walmart on Cobb Parkway South on Monday.