Man found guilty of murdering ex-girlfriend’s fiancé, Cathedral Catholic teacher

Christy Simeral
·2 min read

SAN DIEGO (FOX 5/KUSI) — A jury on Monday found a man guilty of first-degree murder in the death of his ex-girlfriend’s fiancé, a Cathedral Catholic High School teacher.

During the trial, prosecutors said Jesse Alvarez, 33, gunned down Mario Fierro as he was leaving his North Park home to go to work on February 1, 2021. Prosecutors said Alvarez killed Fierro out of jealousy, after the victim got engaged to Alvarez’s ex-girlfriend, Amy Gembara, also a Cathedral Catholic teacher.

Alvarez even testified he had an “unhealthy obsession” following the breakup of a 3.5 year relationship.

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Prosecutors say Alvarez stalked his ex who then moved, changed her number and tried to get a restraining order.

Prosecutors say less than two months before the killing, Alvarez started plotting after learning his ex and Fierro got engaged.

“’I was brewing anger’ – his words. Yes he was. And he continued to brew anger. And what else did he say? That he wanted Mr. Fierro gone or dead,” said McCarthy.

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Prosecutors say Alvarez planned and researched online how to kill Fierro, then ambushed the victim outside his apartment.

Alvarez claimed he went up to Fierro and introduced himself, and that Fierro then threatened to kill him and got aggressive.

Alvarez said he tried, unsuccessfully, to get Fierro to calm down before Alvarez pulled out a gun.

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“If this is premeditated, then he’s just shooting him right away. He’s not trying to talk to him, not trying to make conversation,” said defense attorney Peter Blair.

Prosecutors say Alvarez shot Fierro six times — four times in the head — and argued it was not a case of self-defense.

“Mr. Fierro had no idea the defendant was there and no idea of his presence — had no idea the defendant waited almost an hour for him and watched him and waited right until he had his back to him. He’s a coward,” said McCarthy.

Alvarez is slated to be sentenced on May 10. He faces life in prison without the possibility of parole.

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