Chilling Video Shows 13-Year-Old Murder Suspect Before and After Allegedly Stabbing Mother 46 Times

Earlier this month, NBC 6 Florida obtained doorbell footage from the Hialeah apartment of Derek Rosa, 13, and his mother, Irina Garcia from October 12. One portion of the video was filmed before Garcia's murder and shows her cradling her 2-week-old baby girl as Rosa asks, in Spanish, "Why do you always tell me 'Don't run?'"

Hours later, Rosa would call police and tell them he killed his mother, per authorities.

During the disturbing call, Rosa said his mother was dead and claimed he "took pictures and I told my friends about it," before asking dispatch, "Is that bad?" He also said he was thinking about shooting himself, but "didn't want to." He added, "I'm just really sad. I'm really sad."

While Garcia was stabbed more than 40 times, his half sister -- who slept in a crib just steps away -- was unharmed.

Some of the new footage shows Rosa on the phone with dispatch after Garcia's murder, as he gives police his address before opening the door to look outside the apartment and says, "I see officers, do I leave? Do I leave my house?"

Police placed him under arrest upon their arrival at the unit.

Back in December, the Miami-Dade State Attorney's Office released a number of pictures from the crime scene.

Two of the photos were from the baby monitor in Garcia's bedroom, one showing her holding her newborn daughter and another taken a little more than a half hour later showing Rosa standing over his mother's bed as she slept, the baby in bassinet nearby.

Additional images include a selfie Rosa allegedly sent to his friends after the murder, his hands appearing to be covered in blood as he flashed the "hang loose" sign (below).

Photos of the blood-covered knife used in the crime were also sent out; it appears the tip of the blade broke off.

Rosa is being charged as an adult in Garcia's murder and awaits trial.