A Louisiana woman has pleaded guilty to killing an infant son who had Down syndrome by injecting hand sanitizer into his feeding tube.

Plaquemines Parish District Attorney Charles Ballay said in a news release that 22-year-old Erika Wigstrom pleaded guilty Tuesday to manslaughter. A judge sentenced the Belle Chasse woman to the maximum 40 years in prison without probation or suspension of sentence.

A grand jury indicted Wigstrom on first-degree murder and attempted first-degree-murder charges in the death of her son, Lucas Ruiz. Lucas died of alcohol poisoning in January 2014.

Prosecutors say Wigstrom first tried to kill Lucas in October 2012 by injecting perfume into his feeding tube while he was in the hospital for a heart procedure. He survived, but died after she injected the hand sanitizer.