A man who was in a relationship with missing American woman Priscilla Brooten is in custody to help police with their inquiries, as officers excavate the front yard of their Brisbane home.
Police began excavations at the Bracken Ridge property on Saturday morning after the homicide detectives joined the case.
Cadaver dogs led police to a small area in the front yard for the excavation. A forensic investigation of the home is also underway.
Police believe the mother disappeared in July 2018, but she was not reported missing until December.
Police told the ABC Ms Brooten's 43-year-old partner, who she lived with, was in custody helping with inquires.
They believed the pair had been in a de-facto relationship for a year before she disappeared.
Detective Senior Sergeant Michael Hogan said Ms Brooten was heavily involved in online gaming and he believed her friends in chat groups may be able to help piece together her last moves.
"Police suspect a lot of people she associated with online and also in some private clubs may not know that police are investigating her disappearance," he said.
"Often these people may not have known that she was reported missing.
"Any contact she had with them may help the investigation."
Detective Senior Sergeant Hogan said Ms Brooten has a daughter and mother in California.
He said Ms Brooten, 46, is described as an outgoing, friendly person and a dedicated mother who enjoyed yoga and Zumba.
"We share the fear of Ms Brooten's family and friends and have reason to believe she may have met with foul play," he said.
Saturday's search of the property was not in relation to one single tip-off but an ongoing investigation.
Detective Senior Sergeant Hogan said the excavation would continue on Sunday.
Police used cadaver dogs to locate "where it would be the best place to start the excavation".
He said they picked up a scent "but it does vary … so we still have to investigate it by taking the ground up".
Officers had been in contact with them this morning and "they have concerns because she has not made contact with them for some time".
Police are also appealing for information about Ms Brooten's blue Volkswagen Golf hatchback, which was found abandoned on Bunton Street, Scarborough on July 6 last year.
The car has also been declared a crime scene.
"We are appealing for anyone who may have seen the car being left in the street that night or may have noticed anything suspicious in the area that night to come forward," Detective Senior Sergeant Hogan said.
"Regardless of how trivial you think the information might be, it may be crucial to our investigation."
