A $500,000 reward is being offered to solve the "heartbreaking mystery" of a NSW woman's suspicious disappearance almost 25 years ago.
Marion Barter was last seen at a bus depot on Scarborough Street, near Railway Street, at Southport, Queensland, on June 22, 1997.
Weeks before she disappeared the 51-year-old was seen by a family member leaving a service station on Ferry Road, Southport, in a red Honda Civic Breeze with a tall male passenger.
Inquiries revealed Ms Barter left Australia for the United Kingdom on June 22, 1997, under the name Florabella Natalia Marion Remakel, which she had officially changed a month earlier.
Her outgoing passenger card stated that she was divorced and intended to live in Luxembourg.
Investigators believe Ms Barter returned to Australia just weeks later - on August 2 - with an incoming passenger card stating she was married and living in Luxembourg.
Inquiries also revealed that following her disappearance, someone accessed her bank account.
Family members reported Ms Barter missing to police at Byron Bay in October 1997.
A coronial inquest began in Sydney in June and will continue at Byron Bay this week.
Homicide Squad, Detective Inspector Nigel Warren said a reward for information which leads to the conviction of anyone responsible for Ms Barter's disappearance had been increased to $500,000.
"We are still working to establish Ms Barter's movements and whereabouts upon returning to Australia in late July or early August 1997 and wish to speak with anyone close to her during that time," Det Insp Warren said on Wednesday.
Ms Barter's daughter, Sally Leydon encouraged anyone with information to come forward.
"My mother's behaviour before leaving Australia was out of character.
"She also missed my brother's birthday - something I know she would never do," she said in a statement.
"Something untoward was happening in her life and that thing still remains a heartbreaking mystery for my family today," Ms Leydon said in a statement.
