A woman who was charged with murder over the death of a man believed to be her partner in South Australia's mid-north has been released on bail after the charge was downgraded to aggravated assault.

The 52-year-old man was reported unconscious at a house in Dorothy Street, Port Pirie South, about 2:15pm on Friday, October 3.

"Despite the efforts of paramedics, the 52-year-old man could not be revived and was pronounced deceased at the scene," police said in a statement.

Police had arrested a 42-year-old woman and charged her with murder on Friday night.

But, on Monday, police said that, "following further inquiries and a post-mortem examination", the initial charge laid against the woman was downgraded to aggravated assault.

They said she had also been released on bail.

Police also s

See Full Page