It is understood about 40 koalas have been euthanised or died since the Cape Bridgewater bluegum plantation was bulldozed in late January.

DELWP confirmed as of September up to 68 koalas had been taken to be rehabilitated, 42 of those had been released and the remainder are still in care across two wildlife shelters.

"The Cape Bridgewater Koala investigation is ongoing," the DELWP statement said.

"Complex cases such as this take time. The Conservation Regulator is working through the evidence to determine what happened in this important case.

"To date large amounts of evidence from the crime scene has been sifted through as well as mobile devices and witness testimonies.

"Forensic radiography and pathology has taken place on animals located at the crime scene. Forensic pathology can tell when an animal died and what caused it."

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Mosswood Wildlife in Koroit have released all of the Cape Bridgewater koalas in their care and centre manager Tracey Wilson said the team had been regularly checking up on them.

"They're out in the wild and in a far better state than they were before," she said.

"Last week was a huge week for releasing the koalas.

"We haven't been able to track them because of COVID but we're monitoring them and I've covered a lot of kilometres checking up on them and so have the others.

"We can't do much more than that except hope they don't need to come back to us."

For DELWP to understand the survivability, health and movements of the koalas following their release earlier in the year about 30 were radio-collared, tracked and monitored for around three months at two locations.

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The sites' vegetation health and koala population densities were also assessed as part of the monitoring program.

A report on the translocated koalas' movements is being completed.

The Conservation Regulator will release information on the outcomes of the translocated koalas once the report is complete.

Anyone with information about the investigation can contact Crime Stoppers on 1800 333 000 or make a report online at crimestoppers.com.au.

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