So unlikely.
A psychiatrist ,used to dealing with emotionally and mentally disturbed patients, inviting one into their home.
A doctor, shown a picture of his wife, taken by same psycho, in his home, NOT phoning the police.
A daughter, after being threatened with a knife by same psycho, suddenly believing that her father isn't nice any more.
Same psycho, after threatening to stab everyone, screaming wildly and generally being, ...psycho! suddenly decides he isn't when the surgeon admits to a mistake.
Doctor replacing psycho and kicking seven bells out of the original psycho.
All, or nearly all, living happily ever after.