Maine authorities arrested a Pennsylvania woman on Sunday, a day after her 3-year-old daughter died in a hot car.

Kelly Brown, 40, was visiting family when her toddler daughter and dog were found deceased in her vehicle parked in Milford. The two were left in the car for over 15 hours — which Brown claimed happened after she was swept away into a river while disposing of trash, as reported by WCAU.

Brown allegedly explained that she intended to teach her daughter about environmental protection, as they encountered considerable litter at camping sites during their journey from Pennsylvania to Maine.

She mentioned they paused at a gas station in Milford to tidy up the parking area before leaving her daughter and dog in her locked vehicle to obtain a trash bag, according to WCAU.

The Portland Press Herald reported that Brown’s mother requested a welfare check soon after Brown and her daughter failed to arrive at a relative’s residence in Clifton on Thursday.

Police eventually pinged Brown’s cellphone, leading them to the gas station in Milford — where they found the deceased girl and dog.

Maine State Police said an official determination is pending, but the medical examiner believes Brown’s daughter died from hyperthermia.

Brown allegedly informed police that it took her hours to extricate herself from the river. Officers observed that her attire seemed dry — to which she claimed it was because several hours had passed since she emerged from the river and attempted to return to her vehicle, according to the Portland Press Herald.

Surveillance footage from 6 a.m. Saturday allegedly showed Brown leaving the vehicle at 6 a.m. and returning 15 hours later, WLBZ reported.

Brown was charged with manslaughter. Her bail was set at $50,000.

[Feature Photo: Penobscot County Sheriff’s Office]