BOBIGNY, France - A 33-year-old French man who admitted to killing his wife and their four children claimed he "heard voices" telling him to "cause harm", a prosecutor said on Thursday.

French police on Tuesday arrested a man with a history of psychiatric illness on suspicion of murdering his Haitian-born wife and their children aged nine months and four, seven and 10 years old.

Their bodies had been found on Monday, Christmas Day, at home in Meaux east of Paris.

The man, a plumber, has been receiving treatment since 2017 for depression and psychotic behaviour.

Meaux public prosecutor Jean-Baptiste Bladier, citing the results of Wednesday's autopsy, said the children's 35-year-old mother and her 10- and seven-year-old daughters had received "around 10 stab wounds each" which had been "administered with great violence".

The four-year-old and nine-month-old boys "died of asphyxia following drowning", he added.

After appearing before an investigating judge Thursday, the suspect was formally charged with "aggravated voluntary manslaughter", Bladier said.

In addition, he was charged with attempted murder after telling investigators that he had planned to also kill his father.

The suspect said that he had "not been able to identify a trigger for his act", said the prosecutor. He has "felt nothing" and "felt empty" after murdering his family, the prosecutor added.

- 'Loved his children' -

According to Bladier, the suspect "indicated that he had been taking his daily medication" since 2019, but had not taken it on December 24.

Police discovered the bodies at a ground-floor apartment in a working-class district of Meaux at around 9:00 pm on Monday.

Neighbours told police they had heard cries downstairs during the night of December 24 to 25, adding they had seen traces of blood.

An inquiry has been opened into the murder of minors under 15 years old, and murder by a partner.

The man had been held in 2019 after stabbing his partner in the shoulder blade when she was pregnant with their third child and then trying to kill himself. She had refused to press charges.

The man was arrested near his father's home in the neighbouring town of Sevran.

"He loved his children, he loved his wife," the suspect's father told broadcaster RMC.

"Maybe what he did there was unconscious, that he didn't know what he was doing", he said.

"I don't understand it yet".

- 'No better wife' -

The suspect's sister was more outspoken, saying she had helped raise him.

"There's no one I loved more than my brother, from birth to the age of four," she told RMC.

She blamed him despite his condition.

"No matter how many people tell me he's crazy, I don't give a damn, I blame him," she said.

She described his slain wife Beatrice as "the strong woman, the fighter, a real lioness."

The couple, who had been together for 14 years and married since October 2023, had met in high school.

"She was always there for him, defending him. He couldn't have found a better wife," the sister said.

"She was the one who managed my brother's medication, his medical appointments, his paperwork."

The Paris region has recently seen a series of infanticides.

In November, a 41-year-old man confessed to killing his three daughters, aged between four and 11.