WELD, Maine (NEWS CENTER) -- Police found a stash drugs in the bedroom of a preschooler whose mother had just died.

The investigation began with the death of 29-year-old Elspeth Donnelly. She was originally from Haverhill, Mass. before moving to Weld.

The Franklin County Sheriff's Office said Donnelly was pronounced dead upon arriving at Rumford Hospital early Tuesday morning. She was brought there by her boyfriend, 35-year-old Ian Klanfer with help from 42-year-old Eric Boncore.

Deputies went to Donnelly's home in Weld to try to learn more about how she died. Her three-year-old son was asleep inside, as were two adult guests from Texas. After being woken up, the adults told deputies they were unaware the child had been left alone with them.

A search of the child's room by deputies uncovered a mix of illicit and prescription drugs as well as used syringes. Their findings led deputies to arrest Klanfer on a charge of endangering the welfare of a child. In addition to being Donnelly's boyfriend, Klanfer is also the father of her son.