Karen Perez’s body was found in an abandoned apartment in South Houston, Tex. (Texas EquuSearch)

Prosecutors in southeast Texas said a teenage boy has been charged with murder after he allegedly sexually assaulted and choked to death his 15-year-old girlfriend — while he recorded her cries on his cellphone.

“You can clearly hear the defendant forcing the victim to have sex with him. He even calls her by name,” according to a probable cause statement read earlier this week in court. “You can hear the victim saying she does not want to do this.

“You can hear the defendant choking the victim. You can hear the victim stating, ‘I don’t want to die.’ ”

But Karen Perez was found dead Monday in South Houston — her body partly naked and hidden in a cabinet under a kitchen sink in an abandoned apartment, search-and-rescue crews told reporters.

When asked in court Wednesday whether he killed her, the boy told prosecutors: “Yes I did. That’s all I’m saying,” according to the Houston Chronicle.

He has not been identified because he is a juvenile.

Karen’s family and friends began to worry May 27 when the teen didn’t return home from school.

Authorities said her boyfriend had texted her earlier that day, telling her to skip class at South Houston High School and meet him at the tennis courts, according to the probable cause statement, which was read in court by John Brewer, an assistant district attorney in Harris County.

He told her that if she did not meet him, he would kill her and that her life would “end on bloods,” according to the court documents.

CBS affiliate KHOU reported that surveillance video showed the girl with two boys at a nearby taqueria that afternoon. It was suspected that she then went to an apartment complex by the school, according to the station.

Texas EquuSearch, a volunteer  search and rescue organization, started circulating a missing person flier showing Karen with dark hair and dark eyes. It said she had a small scar between her eyebrows.

The day she went missing, it said, she was wearing white pants and a black-and-white T-shirt.

Her boyfriend’s father drove the boy around to help search for her, according to the court documents, but he told his father to take him home because “she is not alive.”

The father contacted police, and officers seized two cellphones from the boy’s home containing the text messages and a cellphone video, which was blacked out but had working audio, according to the documents.

Tim Miller, founder and director of Texas EquuSearch, told NBC affiliate KPRC that he found Karen’s body Monday night in the apartment.

“I have no doubt this is foul play,” he told the station this week. “I think where we found her is the apartment where things happened.”

Other parents at the school and members of the community told reporters that the abandoned apartments are an “eyesore,” where some students go to have sex and do drugs, according to news reports.

“Now unfortunately a little girl’s body was found in one of them,” Miller told KHOU.

Officials told the station that the apartment complex meets city codes but that they are looking into the issue to see what can be done.

Karen was a freshman at South Houston High School, according to the Pasadena Independent School District. After authorities confirmed that the missing teen was dead, those who knew her expressed their pain.

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“Our deepest sympathy goes to Karen’s family,” the school district said in a statement to KHOU. “The student leaves behind a host of friends who will miss her greatly. As the South Houston High School family mourns the loss of this student, the campus and Pasadena ISD are doing everything we can to provide comfort and assistance to the family and to our students in this time of grief.”

Karen’s family and friends she said will be remembered as a girl who was always excited and smiling.

“I know God is watching right now,” her cousin, Janely Valdespino, told KHOU. “She was the sweetest. She was always smiling and laughing. She was always so happy.”