An Indiana high-schooler was charged with the murder of his pregnant classmate, who was allegedly carrying his child when she was found slain in a dumpster Sunday.

The body of Breana Rouhselang, a 17-year-old former cheerleader in Mishawaka, was discovered around 4:30 a.m. behind a restaurant near her mother's house, hours after her parents reported her missing.

Aaron Trejo, a 16-year-old football player, was booked into the St. Joseph County jail on suspicion of murder, the St. Joseph County Prosecutor’s Office said.

On Monday afternoon, Trejo was charged with one count of murder and one count of feticide. The alleged killer is being held without bond.

Breana was last seen at her home around midnight Saturday, said Lt. Alex Arendt of the St. Joseph County Metro Homicide Unit. Her family reported her missing after they “got the feeling that something wasn’t right,” Arendt told the AP.

The girl knew Trejo from the football team, Arendt said, but the particulars of their relationship were still under investigation.

A probable cause affidavit included the shocking details of Trejo’s alleged plot.

Breana’s mother told cops that her daughter, who was six months pregnant, had gone behind her house to speak to Trejo around 11 p.m. on Saturday. But Breana didn’t come back inside. Her mother woke around 1 a.m. and grew concerned, the affidavit states.

The mother then went to Trejo’s home a few blocks away, but Trejo claimed Breana wasn’t home when he came over to talk with her. “Aaron also stated that he had lost his cell phone so she could not call him back later,” the document alleges. “Breana’s mother continued to look for her and call her friends.”

The mother called police, who quickly visited Trejo. “Aaron Trejo again stated that he had gone to meet Breana but she did not show up,” the affidavit alleges, adding that cops had Aaron send Breana a message on his cell phone.

When cops returned to the alley behind Breana’s home, they found glasses and a stocking cap covered in blood.

Detectives sealed off a perimeter in the area and found more blood, before a thorough search led to Breana’s body. A black garbage bag had been placed over her head and upper torso, the document states.

After the gruesome discovery, authorities transported Trejo and his parents to the homicide unit for an interview. Trejo told detectives that he’d reached out to Breana for the first time in months to see how she was doing with the pregnancy. Breana agreed to meet him, Trejo allegedly claimed, but she wasn’t home when he arrived at her house.

“Aaron acknowledged that he was aware of Breana’s pregnancy and that he was supposed to be the father of the baby. Aaron stated that neither he nor Breana wanted to have the baby,” the affidavit states.

Trejo would ultimately confess to killing Breana, according to police. The teen allegedly told cops that Breana had waited too long to inform him she was pregnant and that she couldn’t get an abortion.

Asked what he did about that, Trejo allegedly replied, “I took action… I took her life.”

Trejo then told detectives that he “stabbed Breana in the heart with a knife he brought from home,” the affidavit states, adding that Trejo “chose to use a knife because he thought it would kill Breana quickly” and used the garbage bag for that purpose.

According to the affidavit, Trejo said he’d been planning Breana’s murder for about a week and hadn’t told anyone. After he killed Breana, Trejo walked to a river, where he dumped her phone and his knife, police say.

An autopsy confirmed Breana died from multiple stab wounds, and that her scarf was on so tightly that she was being strangled before she died.

On Sunday, Breana’s stepmother, Nicole Rouhselang, told reporters that Breana was a softball coach, cheerleader, and football team manager at Mishawaka High School, Nicole said. (Trejo was listed as a varsity football player on the Mishawaka Cavemen’s roster.)

Earlier on Monday, Breana’s father, Dave, waited with Nicole for a call from the Metro Homicide Unit. “We’re all waiting for the call to have a meeting,” Dave told The Daily Beast. “Ready to walk out the door as soon as we get a phone call.”

The couple grappled with their horrific loss and said they were numb as reporters rang Nicole’s cellphone. “We just don’t even know what to think,” Nicole said. “We’re in shock. We’re in disbelief. She was a child with a child. There’s no words to express how I feel.”

Dave called Breana “the most caring, innocent person you could ever meet.” He said his daughter, who was his second child, was “never a mean person. Never an angry person. One of the nicest, most genuine kids.”

The grieving dad said he’d never met or heard of Trejo, but said the killing may have been “premeditated.” Asked if Trejo was the father of Breana’s baby, Dave said, “We’ll have a more clear answer on it later but I do believe so. That in my mind is probably the motive behind this.”

Nicole told reporters on Sunday that Breana’s grades had been slipping lately, and that she had only learned that the teen was pregnant after the killing. “I just don’t understand it,” Nicole said, according to the South Bend Tribune. “She was young… too young to have a baby herself.”

The stepmom told The Daily Beast that she’s known Breana since she was 6 years old.

“She was very caring and loving,” Nicole said. “She would love a fly. She was a lover of animals. She was an athlete. She played softball from the moment she could walk. She was a cheerleader from the time she was little, all the way until this year.”

“ She was very caring and loving ... She would love a fly. She was a lover of animals. ”

Nicole said Breana was a typical teenage girl who had lots of friends from all of her school extracurriculars, including volleyball. Breana talked of going to college for athletic training or sports management, Nicole said.

“We’re all big Notre Dame fans,” Nicole added. “We always have Notre Dame in the back of our head, but you have to have a super high GPA average.” Breana was considering Saint Mary’s College.

The last time Dave Rouhselang saw his daughter Breana, he treated her to a joint birthday party at TGI Friday’s, where he works. “It was a great day,” Dave said. “We just went out to dinner, then went home and spent time together.”

It was the week before Thanksgiving. They didn’t see Breana as often as they liked because of custody agreement with her biological mother.

The family has launched a GoFundMe page for funeral expenses. Dave said he wants to “make sure my daughter has a proper funeral she deserves.”