POLK COUNTY, Fla. -- There is a big battle brewing over just what caused the I-4 pileup Wednesday and why state troopers didn't close the road sooner. The Highway Patrol said they did the right thing; their troopers were patrolling the interstate before the crash and added that smoke from the fire didn't cause the wreck.

---

WATCH REPORT: Investigation To Determine If Controlled Burn's Impact

---

The Division of Foresty launched a full investigation to know for sure.

The deadly 70-car pileup on I-4 could lead to dozens of lawsuits. Now there's a raging battle over whether smoke from a nearby fire or fog blinded the drivers.

"The jury is absolutely still out on whether the smoke from that controlled burn had anything to do with this," said Gary Morse, Florida Fish & Wildlife.

Eyewitness News took a closer look at what happened before the crash. At 7:00pm Tuesday night, the Division of Forestry made a rare call to the Highway Patrol to warn them that the smoke from a controlled burn that got out of control could cause problems for drivers. Two troopers immediately started patrolling the interstate, monitoring visibility, and the Department of Transportation put out signs warning drivers.

At 2:00am Wednesday, the National Weather Service reported visibility dropped from 10 miles to a quarter-mile. Despite having two troopers patrolling the area, the last reported check was at 3:15am and the trooper said it was clear.

The first crash was reported at 4:30am, almost 90 minutes later. When Eyewitness News asked the Highway Patrol where the troopers were, they got defensive.

"As I have said numerous times today, and this is going to be the last time, troopers patrolled the area and continued to patrol the area. Smoke was not a factor," said Trooper Larry Coggins, Florida Highway Patrol.

Troopers said witness and drivers told them it was just fog.

"They said fog set in and laid down on the highway and blinded them within minutes," Coggins said.

The Division of Forestry's investigation is expected to take a week. They'll look at weather reports and interview witnesses.

What's at stake is millions of dollars in lawsuits. If an out of control fire helped lead to the crash, the agency that started the fire, Florida Fish and Wildlife, could face all sorts of litigation.