ride in the days before.

In an email, a woman said she had been on the ride in the same train as Esparza the day before. After all the restraints had been checked and an audible  all clear  given from ride operators, an employee stopped and announced a recheck for car three, she said. Another employee came over, checked the restraint, and the ride was cleared to begin.

Another woman called police and said she had been to the park a week earlier with her daughter. When her daughter rode the Texas Giant, they got into car No. 3 on an unknown color train. The woman told police her daughter's restraint was lowered, but then reopened before the ride left.

The woman provided cellphone video in which police said they could not see the bar reopen, but could hear a  distinct 'pop' sound.  The woman's daughter called out to ride operators, who announced,  Car three is unlocked. 

Officers were able to obtain Six Flags video surveillance for the ride, but reported it didn't provide much meaningful information. The video did not show if the restraint had been properly lowered.

Police concluded that there were no signs of any criminal misconduct that led to Esparza's death and ruled the incident an accident.

Six Flags representatives maintain the ride is safe and there were no mechanical problems relating to the ride before the incident.

 We continue to extend our deepest condolences to the Esparza family,  the amusement park said in a statement Friday.  This was a tragic accident that deeply affected our employees, especially since safety is our highest priority and at the heart of everything we do. 

Six Flags said external and internal experts determined that the Texas Giant was safe and that the accident was not caused by any mechanical failure.

 We added incremental and overlapping safety measures to the ride, including redesigned lap-bar restraint pads and seat belts,  the park said.  We also added a test seat at the ride-line entrance so guests can determine if they properly fit in the restraint system. 

Records show the roller coaster had been properly checked and maintained.

Frank Branson, the Esparza family's attorney, is questioning the police investigation.

 All of a sudden, there's no mechanical record showing it, according to police report,  he said.

He said Esparza's family is still struggling with her death.

 They're working through it the best they can,  he said.  [She was a] wonderful woman who kept family together, and she's gone. 

NBC 5's Ray Villeda contributed to this report.