An eighth-grade honor student confessed to brutally murdering his mother while his newborn sister slept in her crib steps away inside a Florida home, newly released police interrogation footage showed on Friday.

Derek Rosa, 13, also told a Hialeah Police Department detective how he used a “big-sized kitchen knife” to fatally stab Irina Garcia, 39, times on Oct. 12, in footage obtained by NBC 6 South Florida.

“You killed her?” the detective asked in the video, dated Oct. 13.

Rosa, accused of stabbing his mother 46 times, is seen nodding ‘yes’ before being asked what type of knife he used to commit the heinous act.

“It was a big-sized kitchen knife,” Rosa chillingly explained, using his fingers to measure out the size of the weapon while telling the officer the hand was “purple.”

The DA’s office had shared an image of a purple-handled knife with blood stains earlier this month.

“Your mom was sleeping?” the detective then asked the teen.

“Yeah, she was sleeping,” Rosa replied.

The detective jumps ahead to ask Rosa what he did after he stabbed Garcia.

The teen claimed he grabbed one of his stepdad’s two guns from his parents’ closet and “put the magazine in the gun, pulled back the slide,” and “intended to shoot” himself but “couldn’t.”

Rosa’s stepfather, a truck driver, also lived in the apartment but was out of town for work at the time of the killing.

Rosa added that he called an “online friend,” referred to only as “Sweeden,” to say goodbye, still committed to ending his life after stabbing his mother.

He then tells detectives he sent his friend two pictures of his mom and a selfie.

Rosa added that he called an “online friend,” referred to only as “Sweeden,” to say goodbye, still committed to ending his life after stabbing his mother.

Rosa said he again thought about shooting himself but decided to call 911 instead.

He then tells detectives his newborn half-sister slept through the murder and that he never touched her.

The detective then asks Rosa where he cut his mother before the audio is muted.

However, the teen in the video pointed to his neck as he answered the question.

Rosa said his mother screamed during his deadly attack

During the interrogation, the detective points out that Rosa has red stains on his clothes, which the teen shares are blood since he hasn’t changed, and that his hands also still have stains on them from the murder.

When asked toward the end of the video, Rosa requested to use the bathroom and asked for an attorney upon returning.