A psychiatric hospital in Western Australia is in the process of determining how a healthy man came to be held at the facility and injected with antipsychotic drugs after being mistaken for a runaway patient.

The unidentified man was picked up by police on December 16th and brought to Graylands Hospital in Perth because he matched the description of an involuntary patient who ran away two days earlier.

Hospital staff also mistook the man for his mentally ill doppelganger and injected him with a dose of Clozapine — a strong anti-schizophrenia medication often only administered when other antipsychotics fail.

The man subsequently suffered an adverse reaction and had to be treated at nearby Sir Charles Gairdner Hospital.

Meanwhile, the escaped patient returned on his own to the hospital that same day.

"I am very sorry for the distress and hurt that the misidentified man has endured," said Mental Health Minister Helen Morton. "I find it hard to imagine that if proper processes were followed, there is any excuse for such a terrible mistake to be made. I will await the outcome of the clinical review, however people must be held accountable for this dreadful mistake and ensure it never happens again."

The police have launched their own investigation into the identification error.

[photo via Shutterstock]