Adelaide man under the spotlight in two separate cold case investigations

An Adelaide man is under the spotlight in two separate cold case murder investigations, with fears he could be responsible for the murders of two people seven years apart.

9NEWS can reveal major crime detectives are actively pursuing the lead that has emerged during the investigation into the disappearance of 51-year-old Harry Houston.

The Whyalla father vanished in 2009 after visiting a friend less than a kilometre from his home.

Despite extensive searches on the west coast Mr Houston's body has never been found.

A suspect was identified just days after Mr Houston went missing when his four-wheel drive was found in the possession of someone known to him.

That man claimed he'd bought the vehicle, but it's an explanation that's been rejected by both police and the victim's son who confronted the suspect.

"I said well if you did buy this car then why did my dad leave his belongings in his car and my belongings he wouldn't just leave his belongings in our car," Scott Houston told 9NEWS.

During the investigation detectives became suspicious when they discovered the man was also linked to mother-of-two Karen Morton, who disappeared from her Pennington home in 2002.

Her body has also never been found.

"The person has told us a number of versions about her disappearance and that is still be looked at as well," Detective Inspector Phil Linton from South Australia Police said.

9NEWS can't identify the man for legal reasons, but it can be revealed he's now officially regarded as a person of interest in both cases.

Detectives will now review the files as part of the historic cold case review and any new evidence will be forward to the Director of Public Prosecutions for consideration.