Moment Carly Gregg, 15, SMILES as she learns her sentence after being found guilty of shooting her mom in Mississippi

Carly Gregg has been sentenced to two counts of life in prison just 30 minutes after she was found guilty of murdering her mom and trying to kill her stepdad.

The 15-year-old sobbed as the guilty verdict was delivered by the jury on Friday afternoon, just two hours after they broke for deliberation.

But by the time she returned to the court room to hear her sentence, a smile was plastered all over her face again. 

She will serve two life sentences concurrently for the charges of murder and attempted murder, as well as 10 years for tampering with evidence in the case.

The final charge relates to a decision Gregg made to tear a CCTV camera down from her kitchen and hide it in the refrigerator after shooting her mom, Ashley, dead in the home on March 19.

Carly Gregg has been sentenced to two counts of life in prison

By the time she returned to the court room to hear her sentence, a smile was plastered all over her face again

Her legal team unsuccessfully argued she was so mentally unwell at the time of the crime that she should be found not guilty due to insanity.  

They earlier rejected a 40-year plea deal offered by Mississippi state prosecutors. 

The jury deliberated for just 30 minutes on whether she should spend the rest of her life behind bars, with or without the possibility of parole. 

Prosecutor Katherine Newman had urged them not to leave open any possiblity that Gregg could later be paroled.

Ladies and gentlemen she is dangerous. She may look like a little girl, they may have said she is sweet little Carly, but unfortunatley that is not true, she said.

We ask you sentence Ms Gregg to life in prison without the possibility of parole. 

Greggs legal team attempted to argue that she was not guilty due to insanity

The 15-year-old sobbed as the verdict was handed down by the jury on Friday, just two hours after they broke for deliberation

Gregg sobbed as the verdict was handed down

Gregg was comforted by her lawyer as she burst into tears when the verdict was handed down

The court heard Gregg, then 14, kept a journal in which she wrote five beliefs she held, including: there is no God, heaven and hell are false and writing your own destiny

Ms Newman told the jury that it was scarier for her to not know why Gregg committed the crimes, noting that if we dont know why, whats to say it wont happen again?

Gregg sobbed as Ms Newman posed that question, shaking her head and mouthing the word no. 

Earlier, her lawyer was seen comforting her and telling her its going to be okay, to which she responded no, its not. 

The court heard Gregg, then 14, kept a journal in which she wrote five beliefs she held, including: there is no God, heaven and hell are false and writing your own destiny.

Ms Newman on Friday drew the jurys attention to the final two beliefs Gregg had listed in her journal.

These two stand out to me ladies and gentlemen, she told us what her intent was, Newman said, holding a piece of paper as she read the final notes.

You dont need family, and its okay to be evil.

When audio was played of her stepdads frantic call to police after he was shot, Gregg covered her ears with her hands and squeezed her eyes closed

The defense said in closing arguments it was undisputed across five days of the trial that Carly Gregg loved her mom (pictured together)

Gregg was visibly shaken by the verdict on Friday

Elsewhere in the journal, Gregg wrote: I choose fire. It is powerful, beautiful and deadly. These are the traits I desire, so I choose fire.

Greggs defense argued that the journals paint a picture of a mentally unwell child who had repeatedly detailed just how much she was struggling. 

Forensic psychiatrist Dr. Jason Pickett told the jury he had a different reading of the journals in a key expert testimony which annihilated the defense.

He questioned whether this is a personal journal where somebody puts things theyre really trying to keep secret, or is this a budding, articulate author that describes things for theatrical reasons?

Carly was repeatedly described by witnesses as gifted, bright and intelligent.

Dr. Pickett read an entry Gregg had written about hearing voices - a complaint the teen hadnt previously raised with her mental health professionals - and said he was highly skeptical of that.

It seemed more theatrical and making light of something. Patients who really suffer this, they are haunted by it, it is quite torturous to them. They do not trivialize it.

Carly Gregg was a bright and gifted student who loved learning, the court heard

Gregg kept her head bowed on Friday before proceedings officially got underway. Some of her relatives are seen in the background, there to offer support

Greggs legal team have hinged its defense on the claim that the teenager was so haunted by voices, trauma and mental health issues that she disassociated and blacked out for the period of time when the crimes were committed.

In closing arguments on Friday, her lawyers said there was no disputing the fact that Gregg loved her mother and stepfather.

The defense also noted that Gregg had no violent history, and that her actions on March 19 came as a shock to all who knew and treated her. 

Her maternal grandparents have stood by her in the courtroom every day of the trial this week, and her stepfather has also not abandoned her. They all appeared stunned as the verdict was handed down.

When audio was played of her stepdads frantic call to police after he was shot, Gregg covered her ears with her hands and squeezed her eyes closed. 

Greggs mother, 40-year-old math teacher Ashley Smylie was fatally shot in the face

Defense attorney Bridget Todd said Gregg believed her father had both bipolar disorder and schizophrenia, and she had developed a paralyzing fear of turning into him.

Carly worried about that all the time, because thats something her mom worried about all the time, the jury heard.

Her mom frequently worried that Carly was going to end up with the same mental illnesses her dad had, because theyre hereditary.

Experts for the state have questioned whether her dad did have those mental illnesses, or if he had symptoms that presented as such due to his drug addictions.

Both sides described Ashley as a loving mother whose world revolved around Carly.

Carly was the love of her mothers life, they both said.

But Todd said Ashley was also overprotective, in large part because shed already lost one child - a daughter who died from a health condition years prior.

Do you honestly believe that loving, overprotective mother would... put her child on antidepressant medication when she herself had had horrible side affects? 

You cant tell me that Ashley Smylie, as loving and protective as she was, wouldve taken that risk with Carly if it wasnt required.

This was not a bad kid. This was not a kid who was enraged. This is not a kid who had hatred in her heart for her mother or her stepfather, in fact, it was the exact opposite. This was a kid who was experiencing significant mental health issues. The same mental health issues that ran in her family that we know are hereditary, she said.

This is a kid who was compliant with the medication she was put on, however, that medication... caused her symptoms to worsen. And while she was having a state of psychosis in an episode of acute stress on March 19, she lost herself in what was the perfect storm. 

Gregg, who turned 15 in prison but was 14 at the time of the alleged crime, was smiling and giggling beside her lawyer on Thursday morning ahead of the states rebuttal, but within nine hours her entire demeanor had changed.

Gregg giggled and tried to cover her mouth as day four of proceedings got underway on Thursday

She was seen actively fighting back tears on Thursday afternoon, following the testimony of Dr. Pickett.

Dr. Pickett was the prosecutions closing witness, who attempted to systemically dismantle the defense case, one argument at a time.

He told the court he does not believe Gregg has bipolar disorder, and he said his professional opinion was that she was sane at the time of her moms death.

Dr. Pickett said Gregg had some psychopathic traits - a statement he does not take lightly.

She is charming and very likeable, he said. I liked her when I did the interview. I dont like saying these things, he said.

The statements were all disputed by the defenses psychiatrist, Dr. Andrew Clark, who had earlier said he diagnosed her with bipolar two disorder.

He said he did not think Gregg was able to understand the nature of her conduct and appreciate the difference between right and wrong at the time of the incident.