ATLANTA — An exit button inside a walk-in freezer in a downtown Atlanta hotel where a worker was found dead failed to work during an inspection, trapping two people who had to beat on the door to alert someone to let them out, a medical examiner found.

The Fulton County Medical Examiner’s Office has amended its autopsy for 61-year-old Carolyn Mangham to include the new details about the freezer exit button at the Westin Peachtree Plaza.

The hotel’s parent firm, Starwood Hotels & Resorts, has cooperated fully with investigators, Starwood spokeswoman Carrie Bloom said.

The autopsy report, obtained Wednesday by The Associated Press, lists the cause of Mangham’s death as “undetermined” but includes updated information about testing of the freezer exit and also accounts of other workers they say became trapped in the freezer but survived.

“Also of note, within the past 6-12 months, another employee had gotten stuck in the freezer because of the same problem, and had to beat on a back wall in order for someone to let her out,” the autopsy states.

Investigators believe Mangham, who also went by Carolyn Robinson, spent about 13 hours inside the freezer before she was found in March.

“If the decedent had become stuck in the freezer due to an exit button malfunction, no one would have been in the vicinity at the time she was entrapped to let her out,” the autopsy report states.

Mangham worked in the employee cafeteria of the hotel, serving her fellow workers meals.

“Miss Carolyn spent 37 years of her life working at the hotel,” said Wanda Brown, one of her co-workers at the Westin Peachtree Plaza.

“She had been our lunch lady,” Brown said. “She was witty, she had a beautiful smile, and she cared about us. She was loving, she was caring and she was giving.”

The U.S. Occupational Safety and Health Administration is proposing nearly $12,500 in penalties stemming from the death, the agency said this month. The hotel failed to ensure the exit door was “unobstructed,” OSHA said in its citation this month. The agency is continuing to investigate.

“We cooperated fully with all investigations into her death and have received the OSHA report,” Bloom said in a statement. “As the OSHA process is ongoing, we will respond to OSHA appropriately.”

As the case remains “an active OSHA process, we are unable to provide further information at this time,” hotel spokeswoman Sally McDonald said in a statement Wednesday afternoon.

In the two days after she was found dead, more than 30 tests of the exit device on the inside of the door were conducted, and the door opened properly each time, McDonald said in a statement March 24.

However, a follow-up inspection in April “proved the button to malfunction,” the autopsy report states. On that day, an OSHA inspector and a hotel employee allowed the door to close as part of the test, and they became trapped. They had to pound on the door to let people outside know they couldn’t get out, authorities said.

Atlanta police investigated the death, but found there was no criminal activity involved in the case, Atlanta police spokesman Kim Jones said Wednesday.

Workers have died in walk-in freezers in the U.S. — some were trapped inside and others overcome by carbon dioxide vapor — but such deaths are relatively rare, according to OSHA records.

In June 2012, a restaurant owner in Nashville, Tennessee, died of accidental suffocation by carbon dioxide inhalation after becoming trapped in a cooler, a medical examiner found. Jay Luther went into the cooler and the door shut, trapping him inside. The interior door release was broken, authorities said.

In August 2002, a 55-year-old woman froze to death after she became trapped inside a walk-in freezer at a ranch east of Meeker Colorado, Rio Blanco County Sheriff Phil Stubblefield told the AP at the time. It appeared a safety lock on the door of the freezer had failed and trapped her inside, the sheriff said.