A Harbeson woman has pleaded guilty to one count of murder by neglect in the May 2015 death of her infant son.

Casey Layton, 30, will serve 15 years in prison as part of the sentence handed down by Judge Richard F. Stokes.

It’s a case prosecutor Melanie Withers called “the most horrific and tragic case I have dealt with in my career.”

Police began investigating Layton and her partner, Doyle Hundley, 39, after a 911 call in May 2015 reporting that their 3-month old son, Aiden, was suffering a seizure and was not responsive. The boy was flown to A.I. duPont Children’s Hospital in Wilmington, where he was admitted in critical condition with multiple broken bones and a serious head injury.

Aiden remained on life support for five months. An autopsy ruled his death a homicide as a result of blunt force trauma to the head. Police said Aiden had numerous other injuries, including a fractured skull and clavicle, a several-weeks-old left femur fracture and an E. coli blood infection. Police said Layton and Hundley offered no plausible explanation for the injuries.

Withers said the case would have been difficult to prosecute because it is unclear what happened to Aiden and who caused the injuries that killed him. She said Hundley, who pleaded guilty to a charge of murder by neglect in May, admitted to shaking Aiden, knew the boy was having seizures and was undernourished, but neither he nor Layton sought help.

Appearing in Delaware Superior Court Jan. 12, Layton had little to say other than yes or no to the questions Stokes posed. Short, with a stocky build and long brown hair, Layton was flanked by her attorney, Natalie Woloshin, who asked for immediate sentencing after Layton’s plea was accepted.

Woloshin said Layton is cognitively impaired with a low IQ, and at one time she was declared incompetent to stand trial before a second doctor found her competent. She said Layton also suffered trauma as a child. Court records show that Layton and Hundley were longtime drug users. Woloshin said she believed Layton’s sentence was appropriate. Withers also said the sentence is a reasonable and appropriate resolution to this case.

Withers said there were a number of factors that led prosecutors to accept the plea deal and the sentence, mainly related to Layton’s personal history and her mental competence.

She said Aiden was born exposed to legal and illegal drugs; Layton had been consuming drugs while pregnant. Withers said after he was born, Aiden was released to the custody of his parents, to be monitored by Delaware Department of Services for Children, Youth and their Families. However, for a six-week period, the department lost track of Layton and Hundley, she said.

Withers said there is no doubt Layton was aware of Aiden’s injuries and disregarded them, but she apparently was not aware that he was at risk of death. She said there is some question as to Layton’s state of mind at the time.

Besides her prison time, Layton must also serve nine months of home confinement and two years of probation. Layton is also not to have contact with Hundley and was ordered to have no contact with a child under the age of 12.