BRIGHTON, Colo. (KDVR) — The Brighton Police Department has arrested parents in the death of their 23-month-old daughter.

Police said the toddler’s blood contained 10 times the amount of fentanyl necessary to kill an intolerant adult user.

Police said they were called to a home in early January when Alonzo Ray Montoya, 31, and Nicole Danielle Casias, 30, reportedly found their child not breathing and unresponsive.

Brighton Fire, Platte Valley Ambulance, and Brighton police tried to perform life-saving measures to save the girl’s life, but she was pronounced dead.

Detectives from BPD and the North Metro Drug Task Force started an investigation into her death in January. On Tuesday, charges were filed against Montoya and Casisas for child abuse resulting in death and distribution of fentanyl.

Police said the parents allegedly participated in illicit drug activity with the toddler present in the home prior to and after her death.

Casias and Montoya were taken into custody on Wednesday. They were scheduled to appear in Adams County court on Thursday.