The Keira MP has written to Health Minister Brad Hazzard for advice as to why the two men have been housed at the NSW Health facility at Waterfall.

7News reported the men are Michael William Goodridge, who murdered his female carer in 2009 at Moss Vale, and Do Hyun Chong, who beat a co-worker to death at a Wetherill Park factory in 2009.

The report stated that families of other residents were shocked and angry to learn the convicted murderers had been quietly moved to the facility.

"I don't understand why these convicted criminals, individuals who have carried out shocking crimes, cannot be placed into one of the health facilities located within our correctional centres," Mr Park said.

"I wouldn't want my mum or dad to be living with these people and I am sure the Minister or Premier wouldn't want any of their family members to be put in this situation.

"Having to place a loved one in a nursing home is without doubt one of the most stressful and difficult decisions you can make.

"Families shouldn't have to deal with the added stress and worry that a convicted serious criminal is sleeping next to them."

He asked the minister for "urgent advice" as to why the two men were not located in an existing Justice Health facility.

"On behalf of the families I would also like to know if and when these individuals will be relocated to a more suitable facility," he stated.

However health authorities claimed the two men have advanced dementia and have been assessed as "low risk".

A spokeswoman for South Eastern Sydney Local Health District said the centre accepted two men from Long Bay Hospital.

"People with dementia will struggle with gradual, irreversible loss of memory, judgment, functional abilities such as eating and bathing and communication, health," she said.

"The disease will eventually claim their life.

"The men have been at the Garrawarra Centre for some time without any serious incident.

"The Forensic, Mental Health, NSW Civil and Administrative Tribunal (NCAT) assessed the patients and concluded the patients were low risk, particularly in light of their advanced condition.

"All clinical areas at the Garrawarra Centre are contained and secured.

"Forensics continue to monitor these residents while they are at the Garrawarra Centre, with regular reporting required and in the unlikely event their risk assessment changes, they would be returned to the Forensic system."

The Garrawarra Centre website says the accredited residential aged care facility provides "high level care for people with a primary diagnosis of dementia, who exhibit challenging behaviours and cannot be accommodated in a mainstream nursing home".

The centre has "purpose-built, dementia specific facilities" - four cottages with double and single bedrooms.

"We endeavour to maintain a home-like appearance and atmosphere where our residents are free to move around their cottage as they wish," the centre advises.

"A safe and secure environment is maintained by a discreet electronic system."

In 2009, Michael William Goodridge, who was 55 at that time, murdered Carmel George, 38, in an abandoned rail barracks next to Moss Vale train station.

Ms George had been caring for him after a car accident.

In 2012, the NSW Supreme Court sentenced Goodridge to 18 years in jail.

The court heard Goodridge had no memory of the crime because of dementia that would possibly claim his life within six years.

Evidence was given Goodridge was angry at Ms George's rejection of his sexual advances and, under the influence of a mix of drugs and alcohol, repeatedly bashed her against a wall and then inflicted horrific internal injuries.

"They were horrendously violent and savage acts carried out with a determined use of force," Justice Christine Adamson said.

"He utterly abused the goodwill that she had shown him by spending time in hospital and taking him to the barracks."

The judge found that, despite his intoxication and mental issues, Goodridge was aware of what he had done.

Do Hyun Chong, who was 70 at the time, murdered his supervisor and housemate Jong Hwa Park, 32, at a scrap metal factory in Wetherill Park in 2009.

Supreme Court judge Robert Allan Hulme said the victim was subjected to a "savage, brutal and sustained beating" with a metal stake.

During the final blows, Chong had stood on Mr Park's lower back and "mercilessly beat him to death".

Two months after Mr Park's death, and before Chong had been charged with his murder, Chong's car collided with a truck, severely injuring him.

Chong suffered "catastrophic brain damage" that left him with no recollection of the crime.

He was sentenced to a minimum of 15 years in jail.