Toxicology report shows extremely high levels of allergy medication in woman, three children found dead in Celebration home

This browser does not support the video element.

CELEBRATION, Fla. — Toxicology reports for a woman and her three children found dead in their Celebration home show extremely high levels of diphenhydramine, commonly known as Benadryl.

Tony Todt, the family's father, is facing four charges of first-degree murder in the deaths of his 42-year-old wife, Megan, sons 13-year-old Alek and 11-year-old Tyler and 4-year-old daughter Zoe.

The medical examiner has not yet said if diphenhydramine, which can cause drowsiness, contributed to their deaths.

Watch: State to seek death penalty against Celebration man accused of killing wife, 3 children

Overdoses of diphenhydramine can be fatal, and the medical experts said these doses were enough to knock a person out.

Initial autopsy results show three of the four Todt family members were stabbed inside their home in December, though an actual cause of death has yet to be released.

Watch: Documents detail timeline leading up to discovery of bodies in Celebration home

Their bodies were discovered weeks later when federal investigators went inside to arrest Tony Todt for alleged healthcare fraud.

After WFTV reported in January that law enforcement sources said Todt confessed to suffocating his family, the station contacted the medical examiner, who said it can be very difficult to determine post-mortem if a person has been suffocated.