The attorney for a man suspected of killing a well liked teacher in North Park told a jury Monday, Feb. 26 his client fired shots in self-defense after the teacher punched him outside his home.

Mario Fierro, 37, who taught at Cathedral Catholic High School, was shot six times and died Feb. 1, 2021, outside his Kansas Street residence near Monroe Avenue.

Jesse Milton Alvarez, 33, is charged with killing Fierro and has pleaded not guilty. His attorney, Kerry Armstrong, told the eight woman, four man jury Alvarez will testify and tell them why he confronted Fierro.

Fierro was dating Alvarez’s former girlfriend, Amy Gembara, who broke up with Alvarez in Sept., 2019, but Alvarez had repeatedly continued to contact and stalk her by mail, phone and other methods.

“He doesn’t take social cues very well,” said Armstrong. “He just didn’t understand he was supposed to stay away from her.”

Alvarez was diagnosed with autism only after the shooting and arrest in 2021, said Armstrong. He had purchased firearms as “he was concerned for his safety” because there were riots in some cities.

Deputy District Attorney Ramona McCarthy told jurors that Alvarez’s computer searches included “how to shoot someone in self defense,” and “how to commit the perfect murder.”

“This case is very simple,” said McCarthy. “His ex was in love but it wasn’t with him. She was in love with him,” pointing to Fierro’s photo on a screen.

Alvarez is also charged with a special circumstance of murder by lying in wait. If he’s convicted of first-degree murder, he will be sentenced to life in prison without the possibility of parole.

The trial before San Diego Superior Court Judge Daniel Goldstein is expected to last through March 15.

“This case is a horrible tragic case…but keep an open mind,” said Armstrong to jurors. “Religion plays a large part in Mr. Alvarez’s life.”

Armstrong said Alvarez saw a notice of his ex-girlfriend’s engagement online and a photo on social media seemed to show her drinking alcohol, of which he disapproved.

“He believed it was his role to protect her,” said Armstrong, adding that he did not go to Fierro’s home to kill him.

Gembara was the first witness and she smiled when asked about Fierro. “Every day with Mario was a gift. He was genuine. He was very loyal,” she said.

She detailed her break-up with Alvarez, saying “I thought he was a person of faith. I didn’t feel safe.” Gembara said Alvarez talked about committing suicide.

Gembara said Alvarez kept calling her, leaving her messages, attempted to break into her apartment, and she went to court to get a temporary restraining order. When that expired, a judge declined to make the order permanent, so his contact continued, she said.

She moved to another residence, but he learned of her new address. She changed phone numbers several times, and added a doorbell camera at home. Once Alvarez approached her while she was at Disneyland, but she just walked away, she said.

David Lam, who used to live near Fierro, testified he was “woken up by noises,” particularly gunshots. When he looked outside, he saw “a body on the ground,” he added. Lam said he gave police an identification of a vehicle leaving the scene.

The prosecutor said Alvarez, who was staying with his brother in Serra Mesa, had driven his brother’s car to the scene. Police later arrested Alvarez at his brother’s home.