Alexee Trevizo is all smiles at prom three months after dumping baby in trash

Beaming with one arm looped through her boyfriend's arm and the other strategically placed in front of her belly, Alexee Trevizo is the picture of happiness in her prom photos. 

But unbeknownst to the photographer who snapped them, and maybe even the other teens around her, the 19-year-old was hiding a dark secret. 

Just 12 weeks earlier, she gave birth to a baby boy in secret in a hospital bathroom, dumping his tiny body in a trash can, wrapped in plastic bags. 

The boy died before hospital staff found him with the bag 'suctioned' to his little face. 

Alexee, a baby-faced cheerleader herself, insisted she never knew she'd been pregnant. She was allowed to return home from the hospital while police conducted their investigation. 

In the last week of April, when her son would have been three months old, she slipped into a mini-dress and sneakers to dance the night away with Devyn Fierro, her boyfriend of 'nearly three years'.

Alexee Trevizo and her boyfriend Devyn Fierro at Artesia High School Prom on April 22 - 12 weeks after she gave birth to their newborn son and put him in the trash in a hospital bathroom. She was arrested on May 10 and is now charged with murder 

Devyn has not been charged with any crime. Alexee will return to court in September 

The pair had not a care in the world as they walked the red carpet rolled out by Artesia High School for the class of seniors. 

Melody Smith is the local photographer who took their photograph. 

She didn't know at the time what Alexee and Devyn - who was interviewed in the hospital - were hiding. 

'I had no idea about [the baby] at the time but when I looked back on the photos, I remembered her because I remember how unusual I thought it was that she wore such a short dress. 

'She was holding her boyfriend's arm, it was big smiles. They were excited to be at prom. 

'You would never have known,' Smith, who grew up in Artesia and attended the same high school, tells DailyMail.com. 

The pair kept mostly to themselves on 'the walk', as did most of the other young couples, she said. 

'It wasn't until after and then there was some retaliation about the fact she had been allowed to attend that I realized what had happened,' Melody adds, referring to Alexee's alleged murder of the baby. 

Videos taken on January 6 - three weeks before she gave birth - show Alexee Trevizo, 19, cheerleading with an enormous baby bump. On January 27, she gave birth in secret and dumped the infant's body in a hospital trash can. Now, she is charged with murder

Today, the 19-year-old's reality is a lot less jubilant than it was on that spring evening in April. 

She is awaiting her first court date on charges of murder and tampering with evidence, unable to leave her home at certain times of the day. 

She was allowed to return to school to graduate, but didn't attend the ceremony with her peers. 

By then, she had been arrested and booked into the local jail. 

What will be at the heart of the trial is whether Alexee intended to kill the baby - or did kill the baby - or if he was stillborn. 

In her initial interviews with police, she insisted he was 'dead' when he 'fell out' of her. 

She had gone to the hospital with her mother, Rosa Rodriguez, on January 27, complaining of back pain. 

At around 2am, she told nurses that she needed to use the restroom. 

She was filmed by hospital surveillance cameras running down the hall, clutching at her behind. 

January 27: Alexee is shown running to the bathroom in Artesia General Hospital to give birth 

January 27: Trevizo and her mother, Rosa Rodriguez, in the hospital. They both insisted they did not know she was pregnant when police confronted them about finding the infant's body in a trash can 

Devyn Fierro and his mother Melanie are shown in the hospital on January 27. He nodded when police asked if he was the father, and told cops he and Alexee had been together for nearly three years

The interview took place at 4.22am on January 27, around two hours after Alexee gave birth 

After locking herself in the bathroom, she gave birth to the full-term baby boy, separating the umbilical chord in a way that nurses said resembled how an animal might tear it. 

Alexee then wrapped the boy in a plastic bag and put him in the trash, before emerging calmly to make her way back to her room. 

When questioned by one nurse in the hallway about all the blood in the room, she said it was 'her period'. 

Once back in the treatment room, she was confronted by staff. 

She denied knowing she was pregnant - as did her mother - and cried. 

Among her mother's first words to her were: 'Lexi, I told you about this.'  

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