A woman hit a multiple killer with her slippers as she tried to protect her husband from a knife attack, the Old Bailey has been told.
The Robinsons were killed in their home on a secluded estate
Christina Constantinou was in bed with her husband, Koumis, 59, when Daniel Gonzalez broke into their London home.
Gonzalez, 25, from Woking in Surrey, is accused of murdering four people in London and Hove in three days and attempting to murder another two.
He has admitted attempted murder and manslaughter but denies murder.
Gonzalez is accused of killing of Jean and Derek Robinson and Kevin Molloy in London, and Marie Harding in Hove, East Sussex.
He has admitted manslaughter on the grounds of diminished responsibility, but this has not been accepted by the prosecution.
It alleges Gonzalez set out to murder at least 10 people in an area stretching from the south coast to London.
On Thursday, the court heard how Gonzalez had already attacked three other people - stabbing two fatally - when he arrived at the Koumis' house in Frobisher Road, Hornsey, north London on 17 September.
Marie Harding was killed in Brighton on 15 September
"My husband asked whether I heard a commotion downstairs. I thought it was my mother and she wanted something," Christina Constantinou said in a statement read to the court.
She said her husband told her to lock herself in the bedroom but she refused.
"I was afraid. I did not want to do what he told me otherwise how could I help him?"
She said she saw a man with "a big knife" who began fighting with her husband.
"Both were fighting in the corridor. He tried to push the knife into my husband's heart. He hit the man and for that reason it went into his upper arm.
"I got my slippers... and hit that man with my slippers," Mrs Constantinou added.
The defence claim that at the time Gonzalez was suffering from auditory hallucination - voices commanding him to kill - which diminished his responsibility and meant he was guilty of manslaughter, not murder.
The trial continues.