Crucial piece of evidence is discovered after separated couple were found dead in a house in suspected murder suicide in Carramar, Perth

A possible key piece of evidence has been discovered after a separated couple were found dead in their home in a suspected murder suicide.

Mark Stillman, 64, and his wife Lesley, 67, were found dead at a home on Golf Links Drive in Carramar, Perth's north, at 10.40 on Sunday morning, with the authorities saying there was 'no third party' involvement. 

The police had been called to carry out a welfare check on the couple, who were separated but still lived together, when they made the awful discovery. 

Now, a note left behind by Mr Stillman has emerged as a possibly key piece of evidence, the West Australian reported.

A family member found the note, which reportedly said words to the effect of: 'Won't get justice, will die with her'. 

Mark Stillman, 64, and his wife Lesley, 67, were found dead at a home on Golf Links Drive in Carramar at 10.40 on Sunday morning. The pair is pictured

Mark Stillman, 64, and his wife Lesley, 67, were found dead at a home on Golf Links Drive in Carramar at 10.40 on Sunday morning. The pair is pictured

Police have ruled out the possibility of a third party being involved in the deaths of the Stillmans, who had four children.

'Homicide squad detectives have determined there is no third party involved in this tragic incident and WA Police will prepare a report for the coroner,' WA Police said in a statement.

A spokeswoman told Daily Mail Australia there is no ongoing threat.

'Investigators can assure the community there are no concerns for the general public's safety,' she said.

Officers rushed to the couple's Golf Links Drive home over the weekend after being called by concerned family members of the couple, who were both from the UK.

A resident of the normally quiet street said he and his wife spoke to Ms Stillman the day before her death and she had given no indication of any trouble.

'We spoke to Lesley on Saturday morning, she was bouncy, she was going off to pilates with her friends and that's the last we saw them,' he said.

'It will hit home in a few days' time.'

Ms Stillman had recently returned from a trip to Cambodia and Thailand.

Police officers attended the property (pictured) on Sunday and detectives and forensic officers visited the home on Monday

Police officers attended the property (pictured) on Sunday and detectives and forensic officers visited the home on Monday

She had been a volunteer at Guide Dogs WA according to her LinkedIn page and completed a Master of Business Administration at the London Metropolitan University.

Dozens of police officers have been involved in the investigation of the deaths, speaking to locals and asking them for any CCTV footage they have from up to a week before the deaths. 

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