JUST days after what would have been Robert Martinez's 28th birthday, police divers were scouring the bottom of Lake Awoonga looking for evidence which could help lead them to his killer.

It's been more than a year since Mr Martinez went missing from Rockhampton, along with Chantal Barnett, but police say their homicide investigation is far from cold.

Investigators have taken more than 300 statements, investigated more than 1500 leads and are working on 200 more - 50 of which have come in the past month.

Detective Senior Sergeant Scott Moon said police were now targeting that area because a number of witnesses recently contacted police to say Lake Awoonga should be searched.

He also said in the past they had received calls that areas in Gladstone may be relevant to their investigation, but they had only recently been able to validate information, which led to the search on Wednesday.

"Investigations of this nature, that are quite complex, have a tendency to go cold," Det Snr Sgt Moon said.

"This one hasn't. It's still very hot and still moving forward, and we are still confident we've spoken to the person or persons responsible for the murder of Robert and Chantel.

"They should be worried, because it goes to show that we don't give up, the public don't give up and they are providing us with very good information."

By 6am on Wednesday police were at the scene marking out specific areas for the dive squad to search.

They are expecting to be there until Friday, depending on whether any evidence is found.

Det Snr Sgt Moon said underwater searches were extremely challenging, with many obstacles and issues with visibility.

The depths of the search area are unclear, but the deepest point of Lake Awoonga is 40m.

While Det Snr Sgt Moon said they were happy with the progress of the investigation, they were still encouraging people with any information, no matter how small, to come forward.

Anyone with information should contact Crime Stoppers anonymously by phoning 1800 333 000 or visiting crimestoppers.com.au.

Police divers are conducting a search for two missing people at Lake Awoonga near Gladstone.
Police divers are conducting a search for two missing people at Lake Awoonga near Gladstone. Brenda Strong