Queensland police raise reward to $500,000 in missing persons cold case

A fresh plea for information has been issued and the reward has been raised to $500,000 in the search for suspected murdered man Marc Kristian Mietus, who has been missing for 24 years.

Mietus, then aged 21, was last seen alive on Australia Day in 2000 by friends at Booyal Dallarnil Road in Booyal, in Queensland's Bundaberg region

Mietus disappeared 19 days after he moved from Melbourne to Brisbane and picked up a hitchhiker at a truck stop in Gilgandra NSW on January 6, 2000.

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He went on to live in a caravan on the hitchhiker's property at Booyal, which was the last place he was seen alive.

Numerous people were living in caravans or makeshift homes on the property.

Mietus went to a friend's house in Brisbane in the early hours of January 26 and then about 6.30am police say he was described as being "distant and his speech disjointed".

When asked for his rent payment, he stated he needed to go and make a call to his friend to get money.

After he made those calls, he came back to the property and told other residents he was being picked up by a friend.

But he was never seen again after about 10am that day.

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Since then Queensland Police's Homicide Cold Case Investigation Team has made more than 200 inquiries and obtained 104 statements.

Emergency services are searching the 44-hectare property at Booyal tomorrow and police are re-interviewing witnesses.

Mietus' father Kris Mietus has pleaded for anyone with information to come forward.

"24 years of not knowing anything is a really emotional stretch of the family," Kris Mietus said.

"There must be someone out there that knows something about this case, someone knows what happened to my son.

"We would like the people who are response to be brought to justice, we know we will never get him back but we hope this will bring in new information and give our family closure."

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The $500,000 reward is for any information that could bring closure to his family.

It was initially $250,000 in 2015 but the amount was increased today.

Detective Senior Sergeant Tara Kentwell said she believed people knew what had happened to Mietus.

"Police would like to speak with the man seen in a white Ford utility with Victorian registration CNS 194 with Marc on January 18, 2000, about 11.30am at the Shell Service station on the Bruce Highway in Gympie or anyone who has information," Kentwell said.

"We are appealing for any person who observed or knows anyone in the Booyal Childers area in 2000 who owned or drove a Brown XD Ford sedan with a dull alloy bull bar and standard wheels to come forward."