Police issued an alert with a mug shot of the man, who they described as dangerous and stressed should not be approached.
Punchihewa is said to have been inside a bathroom at Hutt Hospital - guarded by authorities - when he managed to get free and sneak out a side door, Stuff reported.
It is not known why he had been admitted to hospital, but that he had been wearing a hospital gown at the time.
Police would later find that he had changed into ordinary clothes taken from a clothesline from a house near the hospital, the publication said.
