TOLEDO, Ohio (AP) — Police say planning for an Ohio murder-suicide that left three children, their grandmother and their uncle dead began at least four days before it happened.

Investigators in Toledo said at a news conference Friday police found receipts dated Nov. 8 for items found in the garage where the five family members died from carbon monoxide poisoning on Monday.

Police say food and coloring books were found in the vehicle where the bodies were.

Police also say the garage windows and doors were boarded up and screwed shut and the garage door opener was disabled.

Investigators and family friends say the murder-suicide appears to stem from a family disagreement over where the children should live. They say notes found at the house indicate the children's grandmother and uncle planned the killings using fumes from a pickup truck.