The average stay in The Thomas Embling Hospital is eight years.

“Offending is like mental illness, it starts to pick up around puberty, and then surges through, adolescence, early adulthood. And after 25, it drops off, you don’t see many new offenders after 25. Same with mental illness.” Professor McGorry said.

Victoria’s hospital for the most acute mental health patients, including those too sick to be found guilty of serious crimes, will undergo a $350 million upgrade as part of Thursday’s state budget.

The Thomas Embling Hospital provides secure clinical treatment for patients within the justice system who have either been sentenced or detained for psychiatric assessment and care.

It also provides specialised care for people in the community with acute needs.

The Fairfield centre provides services for people in prison who need additional mental health treatment — which is about a third of Victorian prisoners.

The hospital has been chronically underfunded and crying out for major upgrades and expansions for years.