A newlywed couple stabbed their neighbour to death after throwing a pan of boiling water and sugar over him.

Colin Skilbeck was attacked and suffered nine knife wounds to the chest after answering his front door to downstairs neighbours Rene Howieson and Kathleen Downey in Edinburgh.

Mother-of-five Downey threw a kitchen pan full of boiling water and sugar solution at the victim before Howieson struck him repeatedly with the knife on March 12 on Gibson Terrace, Fountainbridge.

At some point during the attack Howieson handed the knife to Downey who also used it to stab Mr Skilbeck.

One of the stab wounds penetrated Mr Skilbeck's heart and killed him.

He had answered the door despite his flatmate urging him not to.

At the High Court in Edinburgh 36-year-old Howieson admitted murdering Mr Skilbeck, 41, by throwing the solution in his face and repeatedly striking him with a knife.

Downey, 35, also known as Downey-Howieson, had also faced a murder charge but on Monday the Crown accepted her plea to a reduced charge of culpable homicide on the basis of diminished responsibility.

She admitted killing Mr Skilbeck by throwing the water and sugar at him and striking him with the knife.

Her older sister, Maureen Downey, 40, of Chalmers Buildings, Tollcross, Edinburgh, had her not guilty plea to the murder charge accepted by the Crown.

A judge told the pair: "This, of course, is a tragic case. A person has lost his life as a result of the actings by you."

Lord Armstrong called for background reports on the pair ahead of sentencing them next month, when Howieson will be given a life sentence.

The court heard Howieson and Kathleen Downey, who both had alcohol and substance abuse problems, had married about a month and a half before the killing of their upstairs neighbour.

Downey and her new husband both have previous convictions for possession of a knife.

After the attack, Mr Skilbeck's flatmate made a 999 call and police arrived and began performing CPR on the victim until an ambulance crew arrived.

An emergency medical consultant was summoned, but despite every effort being made to save him the victim died.

Downey and Howieson left the property and were seen throwing items into the nearby Union Canal.

They were traced to a house on Rankin Drive in Blackford and when Downey was detained she asked: "Is he dead?"

Downey, who has been diagnosed with an emotionally unstable personality disorder and post-traumatic stress disorder, and Howieson were both detained in custody ahead of sentencing.