A 13-year-old boy who allegedly stabbed his mother to death in front of her newborn baby has been charged with murder.

Derek Rosa is accused of attacking 39-year-old Irina Garcia while she slept in their home in Hialeah, Florida.

The teenager has been charged with first-degree murder, which means his case will be heard in the adult criminal court system, NBC Miami said.

Hialeah police said officers responded after getting a call from Rosa in which he allegedly said he murdered his mother, at around 11.30pm local time on 12 October.

Officers found Ms Garcia dead in her bedroom next to a cot, where a 14-day-old baby was found unharmed.

In a heavily redacted call to emergency services, the boy is heard asking the 911 operator to send police to his home but he did not know the address.

Asked if his mother is breathing, he replied: “Ma’am, she’s dead,” before adding “there’s blood all over the floor”.

He said his newborn sister was sleeping in her cot. Asked whether he had harmed her, he said: “I did not touch her. I didn’t want to touch my sister.”

Rosa said he wanted to kill himself and had loaded one of his father’s guns but could not do it, according to the audio recording.

At one point, he is heard saying: “Miss, I took pictures, and I told my friend about it. Is that bad?”

He said he did not know this friend’s real name but it was someone he played online games with.

In the audio recording, Rosa adds: “I didn’t delete the pictures off my phone, but I sent them to him, and I told him I was sorry and said goodbye to him.”

The operator asked him why he killed his mother, but his response was redacted.

Asked where else he had stabbed her besides her neck, his reply was also redacted.

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Officials said the baby is his half-sister and that the mother’s husband is the teen’s stepfather, who was away at the time.

In letters to the court, Rosa’s father described his son as a respectful student who was “a good kid, well loved by his friends”.

Rosa could be jailed for life if convicted. The US Supreme Court has ruled the death penalty is unconstitutional for juveniles.

He was remanded in custody at the Miami Dade juvenile detention centre.