The mother of a dangerous fugitive wanted over the stabbing death of a factory worker in Sydney's west has urged her son to hand himself in to police.

The public plea by Carol Cramp, the mother of wanted man Gordon Cramp, 37, comes after the body of a 62-year-old man was found near a paint and soap recycling factory in Dunheved, last Thursday.

Police believe the dead man, named on Monday as Lance Hargreaves, was fatally stabbed by someone he knew, and want to question Mr Cramp about the killing.

Police have issued a warrant for the arrest of Mr Cramp, who's described as being of Caucasian appearance, about 165cm tall, thin build and with very short dark hair.

Carol Cramp on Monday made an emotional plea for her son to hand himself in to authorities.

"I need you to hand yourself in," said Ms Cramp, flanked by senior officers at NSW police headquarters in Parramatta.

"Me and your brother will stand by you and your family.

"Please, just hand yourself in."

Police say Mr Cramp is dangerous, has access to a firearm, and are advising members of the public not to approach him.

Addressing media, Detective Inspector Michael Willing said it was unknown if Mr Cramp was still in Sydney or had managed to flee the state.

"We have information that is coming in but we are keeping our options open and he could be anywhere," Det Insp Willing said.

"Hopefully somebody out there knows where he is and will contact us."

He said police were "very concerned" about the wanted man, describing him as "armed and dangerous".

"It's very important for all concerned that Mr Cramp come forward," he said.

Police from the homicide squad were working "around the clock" to locate the fugitive.