DECATUR, Ga. -- Two nurses and an aide from a nursing home pleaded not guilty in DeKalb Superior Court on Wednesday to charges of felony murder in the case of an elderly World War II veteran who slowly died in front of them.

Last November, the Brookhaven Police Department launched a criminal investigation after an 11Alive News Investigation uncovered hidden camera video and court depositions of nursing home staff who responded to 89-year-old James Dempsey at Northeast Atlanta Health and Rehabilitation in 2014.

RELATED | Murder charge filed after nurses seen on camera laughing as veteran gasps for breath

The 11Alive Investigators obtained both videos in 2017 through public records requests after the family filed a lawsuit in connection with Dempsey's death.

READ | Hidden camera tells true story of how veteran died after calling for help, gasping for air

In February, a grand jury announced formal charges against former nurses Loyce Agyeman of Snellville and Wanda Nuckles of Buford as well as certified nurse assistant Mable Turman of College Park.

Ageyman was charged with felony murder and neglect to an elder person. Nuckles was charged with depriving an elder person of essential services. The grand jury also charged Turman with neglect to an elder person.

PHOTOS | How a senior care facility failed Mr. Dempsey (story continues below gallery)

Each of the three women received an additional charge of concealing the death of another.

In the video, Dempsey can be seen calling out for help repeatedly before losing consciousness while he gasped for air. State records showed the staff took nearly an hour from the time the staffers found Dempsey unresponsive for them to call 911 on the morning the incident took place.

RELATED | 3 nursing staff were seen ignoring the veteran's cries; This is why one was charged with murder

On the video, when staffers had difficulty getting Dempsey's oxygen machine operational when they did respond, Nuckles and others can be heard laughing.

After the indictment of the three staffers, Brookhaven Police Chief Brandon Gurley said the 11Alive News story was key to the reopening of the investigation.

ANOTHER INVESTIGATION | Georgia lawmakers call for action following nursing home resident 'eaten alive' by scabies

“It was very instrumental…because there was information in the news report that you guys aired that our detectives had not seen yet,” said Gurley.

The three women are expected to enter pleas during Wednesday morning's hearing.

Sign up for The Speed Feed newsletter below to get the latest headlines in your inbox each weekday!