Police allege the covert network supplied suicide kits with vet drugs and is possibly linked to up to 20 deaths.

An 81-year-old woman has faced court, accused of helping run a black-market euthanasia network now under national investigation.

Elaine Arch-Rowe appeared in Southport Magistrates Court in Gold Coast, Queensland, on Tuesday charged with drug trafficking and assisting suicide.

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She was granted bail and is due back in court in October.

Queensland Police allege she worked with 53-year-old Brett Taylor and his 80-year-old father in a business known as End of Life Services, based on the Gold Coast.

Detectives alleged Taylor set up a registered charity called Cetacean Compassion Australia Ltd, claiming to help distressed whales.

The charity was allegedly how he accessed the restricted drug pentobarbital used to put animals down.

The trio is accused of supplying the drug through so-called "suicide kits," helping people end their lives outside the legal voluntary assisted dying process.

Police believed the group deliberately targeted vulnerable people and said the operation may be linked to at least 20 deaths, including a 43-year-old man who died at Hope Island in April.

Detective Inspector Mark Mooney said the man had a disability but did not meet Queensland's legal criteria for voluntary assisted dying.

"Queensland has very strict legal processes in place for people who are considering end-of-life options," Mooney said.

"These safeguards exist to ensure proper oversight, consent and protection. Circumventing these processes undermines those protections and puts lives at risk."

Police alleged Taylor charged significantly more than he paid for the drug, calling it a business transaction rather than a compassionate act.

Police said this is just the beginning of the investigation and more charges are expected. Taylor remains in custody.