The caretaker whose autistic ward died under mysterious circumstances after wandering away in a crowded department store pleaded guilty to criminal charges on Wednesday.

Hussanatu Wulu pleaded guilty to a charge of neglect of a care-dependent person and was sentenced to one to two years in prison under terms of a plea deal, the Inquirer reported.

Wulu was in charge of the care of Christina Sankey, 37, who was autistic, when Sankey wandered off as Wulu shopped in a Macy's store on March 6, 2014.

Related link: Caretaker of autistic woman found dead now faces charges

The exact sequence of events that followed has never been established, but Sankey was found dead the next morning on North 57th Street in West Philadelphia after officers were flagged down by a concerned citizen around 6:30 a.m. on March 7.

The cause of death was later ruled to be exposure to cold temperatures.

Related link: Cause of autistic woman's death unknown

“Christina Sankey needed constant supervision, and her Individual Support Plan and companion care needs reflected that," D.A. Seth Williams said in a statement announcing criminal charges against Wulu in a grand jury presentment in April. "Simply put, Hassanatu Wulu failed at her job and didn’t follow her training and emergency procedures, so Christina wandered out into the cold March weather in 2014 to die alone."

A press release from William's office provided some details of what happened on that day:

After leaving the Sankey home, Wulu took Christina with her to Magee Rehabilitation on the 1500 block of Race Street, where she dropped off some paperwork and then went into Macy’s in Center City. Security video shows Wulu walking into the store - with Christina behind her - at 2:25 p.m. Moreover, Wulu was not holding Christina’s hand.

The two arrived at a jewelry table and in a matter of seconds Christina left the area alone because she was not being watched. Less than two and one half minutes after she walked away from Wulu, Christina left the Macy’s through one of the Chestnut Street doors. A video camera at the Walgreens on the 1300 block of Chestnut Street showed Christina walking west on Chestnut Street towards Broad Street. Christina crossed Broad Street against the light and was nearly hit by a car. She then proceeded south on the west side of Broad Street and ultimately out of view of the Walgreen’s camera.

The D.A.'s office said that Wulu did not call 911 for over an hour after Sankey went missing, in violation of her employer's policy, and that she also was required by her job to hold Sankey's hand and keep her "in line of sight at all times."