Published Monday, 04 August 2014
The 19-year-old had been living with her boyfriend in the Hanover Street area of the Co Armagh town when she went missing in April 1989.
A number of searches have been carried out over the years but Caroline's body has not been found.
Officers from the Serious Crime Branch used specially trained PSNI victim recovery dogs which can identify traces of human remains during Monday's fresh searches at Hanover Street.
They said the operation is being conducted under warrant but with the consent of the current owner, and do not believe the current occupant has knowledge of the events of 1989.
Detective Chief Inspector Peter Montgomery, said: "It is more than 25 years since Caroline was last seen and almost two years since the most recent phase of investigative activity resumed.
"Despite all the hurdles posed by the passage of time, I still believe that a form of closure is possible for Caroline and her family."
Ms Graham, who was originally from Newry, had been living in Portadown for about two years before her disappearance around Easter time.
She had been for a night out to the Coach in Banbridge with a girlfriend and he stayed part of the night with her friend in a hostel in Portadown, but was gone in the morning.
Peter Montgomery continued: "I have information that suggests Caroline returned to Hanover Street to get some clothes but she has not been seen since.
"I believe she was murdered some time later and that her remains are somewhere in Portadown."
Police began a major search operation in the nearby Carleton Street area in 2012, searching areas of waste ground and parts of premises including a well.
A range of specialist resources were deployed including victim recovery dogs, probes, scanners, structural engineers and an underwater search team. Nothing of significance was found.
Detectives believe the key to recovering Caroline's remains and catching her killer, or killers, lies with a small group of local people.
Peter Montgomery said: "We are grateful to those members of the community who have given us information. All our enquiries lead us to believe there is more than one person who knows exactly where Caroline is buried. We need them to come forward and tell us exactly what they know."
Police want to speak to two men who gave Caroline a lift in a black Ford XR3i the night she disappeared. The pair, "possibly off-duty soldiers", are not suspects but have not yet come forward.
Information can be passed to police on 02890 700 727 or 07585 22 82 83.
Forensic officers carry out searches of the area. (Pacemaker)
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