A man accused of murdering an elderly man in a “random” stabbing will face a mental health check.

Peter Caldwell, 83, was found unresponsive in the carpark of a shopping centre just off the Pacific Hwy in the Newcastle suburb of Charlestown about 9.50am on Wednesday.

About three hours later, Graham John Norman, 53, of Hamilton South, presented himself at Newcastle Police Station around 1pm.

Know the news with the 7NEWS app: Download today

He was arrested and charged with murder and assault with intent to rob with an offensive weapon causing grievous bodily harm.

NSW Police allege Norman stabbed Caldwell multiple times over 20 minutes before fleeing the scene.

Passersby attempted to assist Caldwell, but he died in the carpark.

The men did not know each other, and police have described the attack as “random”.

A knife was recovered from the scene and will undergo forensic testing.

Caldwell has been remembered as a person of “very good character”, The Newcastle Herald reported.

An acquaintance described him as a “lovely, caring man”.

“Always out doing things to help others,” they added.

Norman did not appear when his matter was briefly mentioned on Thursday.

His Legal Aid solicitor requested a mental health assessment for him, saying it was his first time in custody.

He is scheduled to appear before Newcastle Local Court on October 22.