Ambulance Tasmania paramedics left a woman with a history of mental illness alone in her home without electricity, hot water or lighting before she was found dead months later, in a move a coroner has labelled "difficult to understand".

Coroner Simon Cooper has handed down his assessment of the 2018 death of 59-year-old Rosetta woman Kim Szemes, finding she died between 28 May and 8 October 2018.

Mr Cooper found a cause of death could not be determined due to the advanced level of decomposition of the body when it was found.

According to the report, neighbours of Ms Szemes called police to perform a welfare check on May 28, after not seeing her for several weeks.

Police entered the residence through a window, finding Ms Szemes in bed wearing a beanie and covered in blankets in an attempt to keep warm.

They noted she was "incoherent and struggling to speak," and called for an ambulance.

Police left after paramedics arrived, on the understanding that Ms Szemes would be transferred to the Royal Hobart Hospital.

Instead, paramedics later left Ms Szemes alone in bed because she asked them to leave — despite a lack of electricity, hot water or lighting, the fact that Ms Szemes was difficult to understand and repeating sentences, had minimal fluid intake in recent days, and was unable to tell paramedics how or when she washed, Mr Cooper noted.

Body discovered by son

The Ambulance Tasmania case description showed attending paramedics recorded that Ms Szemes' behaviour was "bizarre," her responses "inappropriate," facial expressions were "flat and non-responsive," and her speech content was "bizarre/irrational with repetitive questions/statements and an inability to have a coherent conversation".

Coroner Cooper wrote that because of those observations, it was "difficult to understand" why paramedics then left.

He said nothing in the Ambulance Tasmania records indicated the paramedics considered whether Ms Szemes had the capacity to make an informed decision to refuse treatment.

There was no evidence anyone else saw Ms Szemes alive after the paramedics left that evening.

Months later, in October, Ms Szemes' son Paul arrived in Tasmania to attend a friend's birthday party and visited his mother's house three times over three days without being able to contact her.

On the third visit, he forced entry to the home and found his mother lying on her bedroom floor.

Coroner Cooper found Ms Szemes died between 28 May and 8 October 2018, and that it was likely she died closer to May than October due to the state of her body when it was found.

He did not make any comments or recommendations.

Ambulance Tasmania has been contacted for comment.