Detectives are working to establish how long a 13-year-old girl was alone on a boat before she was found and the bodies of her mother and her partner were recovered from a river.
Detective Superintendent Jes Fry, head of the Norfolk and Suffolk major investigations team, said inquiries are ongoing into how long each of the couple was dead before they were pulled from the River Bure on Sunday.
He refused to comment on reports that the mother, who has not been named, had been dead for several days.
But it is understood that the girl, who was found alone and unharmed on board the family's rental boat, was cared for and fed throughout last week. It is not thought she was locked inside the boat.
Post-mortem results have shown the woman died before entering the water, probably as the result of strangulation.
The man died primarily as a result of drowning. It is thought he committed suicide and might have also used another method, such as an overdose.
Mr Fry said: "All circumstances point towards this being a domestic incident and we will continue to investigate in order to put a full set of evidence before the coroner.
"The girl has been interviewed by specialist officers. Her welfare is our paramount concern and we will continue to support her and her family."
Police divers launched a search after officers, alerted by a boat hire company concerned that one of its vessels had not returned, found the woman's daughter alone on the boat moored in an isolated inlet between Wroxham Broad and Salhouse Broad.