The speeding SUV that caused a deadly weekend crash on the Long Island Expressway in Manorville — which claimed its sixth victim Monday — swerved off the roadway to avoid hitting traffic that had slowed in a work zone, investigators said.

The latest casualty, Helen Adelson, 71, of Westhampton, was a retired dental hygienist who previously lived in Roslyn, her family said. She died Monday afternoon at Stony Brook University Hospital, according to the hospital and police. 

Suffolk police Chief of Detectives Gerard Gigante said several witnesses to the crash, which also left five injured, told investigators an eastbound Subaru Outback was speeding before it careened across a grassy median, went airborne and struck two cars — a BMW and a Honda — traveling west about 9:35 a.m. The Subaru’s driver, Carmelo Pinales, 26, of Hicksville, was among those killed in the crash.

“It looks like traffic may have slowed. . . . It appears he came up fast on a vehicle in the left lane and he moved to the left in an effort to avoid that vehicle, and when he did that, he ran up on the shoulder and continued going across the grassy median and lost control of the car,” Gigante said. “All indications are that he was going above the speed limit; he was speeding.” 

Gigante said the road construction, which wasn’t active at the time of the crash Sunday morning, had caused traffic to slow. The construction, on a section of the road that passes over a Long Island Rail Road track on an incline between Exits 68 and 69, is “pretty well marked” with signs and cones, Gigante said. 

“There are two strips of that road that have been torn up and replaced in the section with metal plates, and bound up on the edges with blacktop,” Gigante said. “There’s a slight rise in the road, over the bridge, to smooth out the plate. If you’re going on it at a high rate of speed, it could be a contributing factor.” 

Adelson’s husband, Isidore Adelson, 81, of Westhampton, a retired truant officer in New York City, died Sunday night. The Adelsons were on their way to a wedding in New Jersey with a couple from their synagogue at the time of the crash, family and synagogue leaders said. 

“They were wonderful partners in the development of this phenomenal, extraordinary Jewish community,” said Rabbi Marc Schneier of The Hampton Synagogue in Westhampton Beach, where the Adelsons were congregants for 20 years. 

Scott Martella, 29, of Northport, who worked as the communications director for Suffolk County Executive Steve Bellone and was previously a staffer for Gov. Andrew M. Cuomo, also died in the crash. 

Also killed were Carmelo Pinales’ sister, Patricia Pinales, 27, of Westbury; and Carmelo Pinales’ son, Christopher, 10. Carmelo Pinales and his sister were pronounced dead at the scene and Christopher died Sunday night at Stony Brook University Hospital, police said. 

The State Department of Transportation is cooperating with the police investigation to examine whether road conditions were a factor, as the agency normally does in crashes leading to fatalities, officials said.

That section of road is part of a $10.9 million multistep project to repair the expressway’s bridge over tracks for the Long Island Rail Road that passes over the Carmans River by Exit 67 and at the highway intersection with Wading River Road by Exit 69, DOT records show. The work should have been completed by July 20, but is delayed, with an overall completion date now expected to be Dec. 31. 

Work in the section of road near the accident, though, is expected to be done next month, with the metal plates expected to be removed. Delays were caused by bridge joints not matching the design work for the project, said Eileen Peters, a DOT spokeswoman. 

The plates on the road were tapered with asphalt at both ends to ease the bump for passing vehicles and the patched section is set up to handle vehicle speeds of 65 to 70 mph, well above the posted limit, she said.

Construction had been shut down for the weekend, so no crews were at the site when the crash happened. Peters said there are signs on the sides of the road warning motorists about the work zone ahead.

The Pinales’ were on their way to the Riverhead water park Splish Splash, their family said.

Patricia Pinales’ 3-year-old daughter had non-life-threatening injuries, police said. 

Martella was driving a 2014 Honda with his fiancee, Shelbi Thurau, 29, of Northport, as a passenger. Thurau was transported to a hospital, where she was treated for non-life-threatening injuries, police said.

Marvin Tenzer, 73, the driver of the BMW that Adelson and her husband were in, and Winnifer Garcia, 21, of Hempstead, who was traveling with others in the Subaru, remained at the hospital Monday and their conditions were upgraded to fair, said Melissa Weir, a hospital spokeswoman. Sandra Tenzer, 69, the wife of Marvin Tenzer, was in the BMW and sustained non-life-threatening injuries.

Gigante said police don’t believe there was any racing, and there were no indications drugs or alcohol were factors, though investigators are awaiting the medical examiner’s report. 

Gigante also dismissed the possibility that an oil spill Saturday night might have impacted the crash. “We don’t have any indication that there was an oil spill that was related to it,” said Gigante. 

Manorville Fire Department Chief Sal D’Amato, who was among the first wave of first responders on the scene, also said Sunday that the oil spill on Saturday night did not appear to be a factor. He said it didn’t occur in the same area as the crash and had been cleaned up with a “speed dry” agent. 

With Víctor Manuel Ramos