A 54-year-old man has been committed indefinitely to a psychiatric hospital for killing his partner and her father in a knife attack after believing that they had turned into “replicas”.

Achilleas Costa, of no fixed address, stabbed Fernanda Assis, 31, and Joanilson Souza De Assis, 61, to death in Wood Green on November 27 2021.

The Old Bailey heard on Friday (June 16) that Costa was apprehended by police after he was seen “behaving strangely” on the pavement outside a Wetherspoons pub in Huntingdon, Cambridgeshire, at around 6.20am on November 28.

William Emlyn Jones KC, prosecuting, told the court that police were called after Costa was seen “muttering” to himself, and was “kneeling to pray”.

He had a plastic bag on him with £1,315 and three bankcards in Ms Assis’s name, the court heard.

Enfield Independent: Achilleas CostaAchilleas Costa (Image: Met Police)

The prosecutor said Costa told police that he had travelled to Huntingdon from an address in Mayes Road, Wood Green, by taxi, and that “his beliefs” had required him to bring the cash with him and to pray outside the Wetherspoons.

Costa told the officers that his girlfriend had gone out and on her return was “not herself” but had instead taken on the appearance of her “mother” or a “paranormal creature”, Mr Emlyn Jones said.

“He said he had been attacked and had been compelled to defend himself."

He also told police that “someone’s been attacked”.

When asked by who, Costa said “me”, before adding that they “looked strange and they were looking at each other in a strange way”.

Eventually, Costa gave police the home address of his partner and her father.

When police attended the address in Mayes Road, Wood Green, they were met with a “dreadful scene”, the court heard.

“There they found the dead body of Fernanda Assis in the hallway, and the dead body of her father in the bathroom,” Mr Emlyn Jones said.

“It was obvious that they had been dead for at least several hours.”

He said that the victims had been stabbed “multiple times” to the “face, neck and body”.

He told the court that Costa’s account was that he had been attacked by his partner and her father, who had been transformed into “replicas”.

“The essence of his account was that he was attacked by two persons with knives, and that he grabbed one of those knives and “pushed them back” with it, stabbing them both,” he said.

“He seemed adamant that neither of them had been Fernanda.”

Costa said that his victims’ eyes were “different” and that it “wasn’t Fernanda”, while Joanilson was “radio controlled”.

Costa pleaded guilty at the Old Bailey last February to manslaughter.

He had been charged with murder, but the prosecution accepted his guilty plea, by reason of diminished responsibility, in light of psychiatric reports.

The court heard evidence from Dr Jonathan Hafferty, a psychiatrist who assessed Costa.

Dr Hafferty told the court that Costa suffered from “paranoid schizophrenia” and that cannabis use had been a “contributor” to his illness.

“In summary, I believe that cannabis is a contributor to his illness and is something that in the future must be avoided,” he said.

He agreed with Mr Emlyn Jones that Costa was “an extremely dangerous man”.

In an impact statement read out to the court, Ms Assis’s aunt, Celia Haddon, said she felt “shock” and “agony” when she heard about the killings.

“My reaction was total shock and agony,” she said.

“I could not believe that the young woman I had known and loved had been so cruelly killed and taken from us.”

She described her niece as “gullible, naive, and desperate for affection”.

In his sentencing remarks, Mr Justice Murray said that he was “satisfied” that Costa was suffering from a mental illness, “namely paranoid schizophrenia”.

He committed Costa to Broadmoor psychiatric hospital indefinitely.

Reporting by PA.