Rosy Esparza, 52, died Friday at Six Flags Over Texas after falling from the large wooden and steel ride.
Ken Martin of KRM Consulting in Richmond, Va., said the investigation into what caused the woman to fall out of the roller coaster could take months.
Investigators will have to sift through thousands of documents and interview hundreds of witnesses to the accident, the Fort Worth (Texas) Star-Telegram reported Sunday.
Jerry Hagins, an official with the Texas Insurance Department said the department will first rule out a mechanical problem, then the investigation will turn toward the actions of employees operating the ride.
Carmen Brown of Arlington, Texas, told The Dallas Morning News she was right behind the victim when she was boarding the coaster. She said park employees told the woman she was safe if she heard her safety belt click.
"Everybody else is like, 'Click, click, click.' Hers only clicked once," Brown said. "Hers was the only one that went down once, and she didn't feel safe, but they let her still get on the ride."