A relative of a mother of five who vanished in Queensland believed the woman's disappearance might have been linked to the Russian mafia, a bag of ecstasy and $80,000, an inquest has heard.
Kathleen O'Shea, 44, who was living in Melbourne at the time, had been staying in the Atherton Tablelands, inland from Cairns, for the birth of her grandchild when she disappeared on December 29, 2005.
On Tuesday, Ms O'Shea's former partner John Parmenter told a coronial inquest in Cairns a relative believed a bag of ecstasy, $80,000 and the Russian mafia might be linked to Ms O'Shea's disappearance.
"But I didn't know if it was truth or fiction," he told the court, adding he didn't tell police about the possible link at the time.
He wasn't told what happened to the drugs or cash, or why Ms O'Shea might have been linked to Russian gangsters.
Mr Parmenter said the relative had spotted two vehicles near their property in the Atherton Tablelands about the time Ms O'Shea vanished.
He told the inquest he had heard rumours that a person known to Ms O'Shea was involved in her disappearance.
Another witness, Ms O'Shea's longtime friend John McKenzie, said he was disappointed the search for Ms O'Shea had been "hijacked" by a family dispute soon after her disappearance.
Searching for answers, Mr McKenzie, who lives in Melbourne, visited the Atherton Tablelands and spoke to Ms O'Shea's friends and family about a year after she went missing.
He told the inquest he felt everyone told him the truth and it was unlikely any of them had anything to do with her disappearance.
"I can't see her giving anyone a reason to kill her," he said.
"She's a bloody beautiful person and I'd be really happy to find out what happened to her."
Mr McKenzie said it was unlikely Ms O'Shea had just taken off because she loved her children too much not to make contact with them.
Although Ms O'Shea was a bit eccentric and regularly hitchhiked, she wouldn't have gone home with someone who had given her a lift, he said.
Ms O'Shea's son Daniel, who was 16 when his mother vanished, said it appeared his mother "disappeared into thin air" and there were no clues as to what happened to her.
On Monday, an arrest warrant was issued by Northern Coroner Jane Bentley for a person of interest in the case.
The warrant, which requires the person to give evidence at the inquest, was reportedly issued after a detective told the inquest the person displayed "strange" behaviour and refused to give a statement after Ms O'Shea's disappearance.
The person, who can't be named for legal reasons, will give evidence via video link on Wednesday morning.
The inquest continues.