Her 39-year-old husband Graham was found dead in the garage of the couple's home in Coltsfoot Drive, Chorley.
Police said that Mr Weller, who worked for a haulage firm in Leyland, had gassed himself to death with car exhaust fumes and left a note.
They added they had evidence to suggest Mrs Weller had been killed upstairs in the house but they were not in a position to confirm an exact location. A small vegetable knife, believed to be the murder weapon, was found inside the couple's red Audi parked in the driveway of their home.
Mrs Weller's body was found in the boot of the car, where she is believed to have lain for several days.
Toxicology results are needed to confirm the exact cause of Mr Weller's death but it is expected they will show he died of carbon monoxide poisoning.
The couple are said to have married two years ago at Chorley Registar Office.
