The family of Claremont man Dino Hadzic, who went missing from his St Georges Terrace office on Monday, has issued a frantic public appeal for information.
Mr Hadzic, 32, caught the train to work from Loch Street train station, turning up as normal at 7am on Monday to his job as electrical draughtsman for BHP Billiton.
He was wearing business clothes, topped with a dark leather jacket.
He greeted colleagues in a normal manner, his brother Edo Hadzic said. Police checked his computer records, which showed he logged on and began work as usual.
CCTV footage shows he left the office at 9.25am. Colleagues said he left abruptly and without explanation.
His close family and vast circle of friends have not seen or heard from him since and are deeply afraid for his welfare.
He had gone to his parents' house in Churchlands while they were out at a movie on Sunday night and talked with his younger brother.
He had promised to return for dinner with the family on Monday night.
Mr Hadzic had been under stress recently, getting a new job, moving house and beginning a new course of study online outside of work, his family said.
"He seemed a bit down. That prompted me to ask if he was coming for dinner. He said he was. That comforted me somehow," his brother said.
"The idea that he would just go missing, he has never done anything like this."
His parents said he was a responsible person who was committed to his work and his family.
"We support each other in every situation," his father, Fazlo, said.
"Our bonds are strong. Family is very important to us. We never have any serious issues ... we don't disagree, our family is always very calm. Dino always has support from us and he supports us as well.
"He is our life."
His mother, Bozena, said her son was kind, gentle, sociable, honest and caring.
"You would never find anyone who would say a bad thing about Dino. Every minute is too long for us," she said.
"I just want him back."
Mr Hadzic's car is still at his apartment. Police are checking records of domestic flights.
His many friends have spent the time since his disappearance combing the streets around his house and sharing Facebook posts and photographs of him.
He is about 185 centimetres tall and slim, with brown hair, pale olive skin and blue eyes.
Anyone with any information is urged to call police on 131 444.