A Florida man stabbed his fiancée to death near their wailing infant in a murder-suicide after learning that she had been unfaithful, according to a new report.

Carlos Diaz, 25, flew into "blind rage" May 26 when he murdered Amanda Hicks, 26, then turned a gun on himself in their Port St. Lucie apartment as their 11-month-old daughter Alani cried in her crib, the teacher's friend told the New York Post.

"She said they were working through it," Hicks' friend said. "But I think that was an issue, among others, and he just went into a rage. A blind rage." 

The couple had been together for about three years after meeting at a Port St. Lucie school where they both previously worked.

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Amanda Hicks, her fiancee Carlos Diaz and their infant daughter, Alani.

Carlos Diaz, right, killed middle school teacher Amanda Hicks in a murder-suicide after he learned she'd been unfaithful, according to a report. The couple share an infant daughter. (Martin County School District/Facebook/Martin County Sheriff's Office)

But their relationship had deteriorated, and Hicks had recently had an abortion after Diaz's family became suspicious he wasn't the father, sources told the newspaper.

Diaz learned Hicks had cheated on him several months ago, but she had dismissed her infidelity as a slight transgression, multiple sources said.

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Hicks deleted her social media pages at the time as Diaz fumed. After she became pregnant, she insisted the child belonged to Diaz. But his family, with whom they were living at the time in Stuart, Florida, had doubts, and she aborted the child. 

"We knew he had a history of being aggressive," a source said. "So, we were worried. But she told us they were working through it, that they would be OK."

Amanda Hicks at the beach in a bikini and smiling at the camera in a portrait

Florida teacher Amanda Hicks, 26, was stabbed to death by her fiancé in a murder-suicide while her infant daughter was home.  (Instagram/Angelink)

Living with his family in a crowded apartment had inflamed tensions, and her excessive drinking had become a point of contention, friends told The Post. 

Three weeks before the murder-suicide, the couple moved into the Port St. Lucie apartment with their little girl to try to repair their floundering relationship.

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"They were in love," a source said. "Amanda had been in some bad relationships with really controlling boyfriends. But she was so happy with Carlos."

But a friend of Diaz said he was no longer committed to salvaging their relationship. 

"He wanted full custody of the baby and was trying to sort out how to do that," the source said. "She didn’t know, but he was going to separate from her." 

Amanda Hicks and her brother Eric Hicks wear Santa hats.

Slain Florida teacher Amanda Hicks poses with brother Eric Hicks. (Facebook)

Diaz's plans took a tragic turn the morning of May 26. He repeatedly called a family member, who didn't pick up. A short time later, a neighbor reported hearing piercing screams. 

"We figured it was just a fight. You get a lot of that around here," the neighbor told the Post. 

A Ring camera captured the sound of a single gunshot at 12:47 a.m., which is when police believe Diaz shot himself. Alani was in her crib near her parents' lifeless bodies for 11 hours before police arrived after a relative requested a welfare check.

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They heard the child crying and kicked in the door. Alani has since been placed with Diaz's parents.

Before the couple began dating, they both had minor scrapes with the law. Diaz had a 2020 assault case from an altercation at a bar, while Hicks was twice charged with driving under the influence in 2019 and 2021, records show. 

Police cruiser in front of a yellow caution tape.

A Port St. Lucie Police cruiser outside the apartment complex where teacher Amanda Hicks was killed in a murder-suicide May 27. (Port St. Lucie Police Department)

Hicks' mother died of cancer several years ago, and she'd never known her father. In 2019, she began teaching sixth- and seventh-grade reading at the Dr. David L. Anderson Middle School in Stuart.

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"We are all still processing," a friend of Hicks said. "We’re in shock, we can’t believe that he would do this. That beautiful baby was the spitting image of both of them. It’s just tragic."