The 25-year-old Indigenous inmate, who had been in jail since May 2015, was found dead in his cell by another prisoner at the Alexander Maconochie Centre about 11am on May 27, 2016.

Two days earlier, Mr Freeman had seen Dr Luke Streitberg at the jail's health clinic requesting to go on methadone. Mr Freeman told the doctor he had been smoking heroin and was considering injecting the drug. He also complained of withdrawal symptoms, and said he had incurred drug debts, the inquest has heard.

Dr Streitberg, a medical specialist at the jail, gave evidence at the inquest on Thursday, telling the court it was not unheard of for a prisoner to develop opioid dependency while in prison.

He said under-prescribing, or declining to prescribe, a prisoner who was opioid dependent came with risks. If the dose is too low, an inmate might seek illicit drugs to satisfy their cravings.

"When you add that to methadone, it's vastly more likely to result in an overdose," he said. "So you have to strike a balance."

Using needles presented a real risk of blood-borne disease, and standover by other inmates posed significant risk of harm, he said.

Dr Streitberg said doctors weren't consulted on an administrative decision to lower the starting dose of methadone from 30mg to 20mg following Mr Freeman's death, and it had caused a "significant degree of controversy" among the prison medical staff.

The court has heard evidence Mr Freeman, who had admitted using the ice and cannabis, had had limited exposure to opioids like heroin, and may have mislead the doctor about his dependence.

The doctor said he took prisoners who approached him in good faith, but "some people are very, very good at presenting in a manner that is very convincing, and objectively testing this is difficult."

He was quizzed on attempts to objectively verify Mr Freeman's word.

The doctor explained, for example, that he did not subject Mr Freeman to urinalysis because the bedside test can be influenced by drugs such as Pandeine Forte and can only pick up recent drug use.

More detailed laboratory tests took weeks to come back, he said, and guidelines said doctors should not wait on the test to prescribe.

One of the questions the inquest has considered is whether Mr Freeman was adequately supervised in the hours and days after his first doses, a period the court has heard is the most dangerous.

The doctor said you had to assume that eventually a person on methadone would have an adverse reaction, "so the onus then relies on the follow up and observation to make sure the patient is not demonstrating significant toxic effects."

He said once doctors started a prisoner on methadone, observations in the prison were made by the nursing staff, and to a lesser extent the other detainees and correctional officers.

Another question the inquest has considered is whether Mr Freeman had accessed methadone outside of the prescription. There is evidence he had at some point had a "few drinks", that is, methadone regurgitated from another prisoner's dose.

Determining what doses he had in the days before death has proven difficult. An autopsy found low levels of methadone in his blood. But the inquest has heard from several experts that the measure is unreliable in determining the level of methadone in blood at death.

"There's a number of changes that occur post-mortem that usually increase concentration of methadone in blood," Professor Olaf Drummer, a forensic pharmacologist, told the court. You cannot backdate the level to time of death, he said.

The hearing continues before Coroner Robert Cook.