A Mental Health Crisis. An Officer’s Gun. A Too-Common Tragedy.

The San Antonio Police Department, like the police in other cities, has a Mental Health Unit available around the clock to respond to calls that require trained, empathetic responses and support for people in distress.

None of the mental health officers on duty were dispatched before Melissa Perez was shot and killed in her home last month by three police officers. Ms. Perez, 46, was exhibiting unusual behavior and had been diagnosed with schizophrenia.

Like the incident in New York in which Raul de la Cruz, 42, was shot six times and critically injured in March by officers 28 seconds after their arrival, Ms. Perez’s shooting is renewing vexing questions about police staffing, training and decision-making, and how officers deal with people experiencing mental health issues.

The police arrived to Ms. Perez’s apartment complex shortly after midnight in late June, after receiving reports that she was cutting fire alarm wires outside her apartment. A lawsuit filed by her family after her death said she told police at the scene the F.B.I. was using the alarm to spy on her. According to video from the scene and police reports, when officers tried to get her to go into their car, she ran into her apartment and locked the door.

While inside her apartment, police video shows, Ms. Perez argued with the officers outside. She threw a glass candlestick toward an officer on the other side of an open window. Then, Ms. Perez, while still inside her home, grabbed a hammer and swung it toward the officers outside. Three officers, Sgt. Alfred Flores, Officer Eleazar Alejandro and Officer Nathaniel Villalobos, shot into her apartment, hitting her at least twice. Within 24 hours, each officer was charged with murder.

The cases have been assigned to the civil rights division of the district attorney’s office, which will review and present evidence to a grand jury that will decide whether the officers will be indicted.

William McManus, the chief of the San Antonio Police Department, said Ms. Perez’s death was the result of the officers’ failure to follow procedure — not a sign of systemic problems.

“The Mental Health Unit was not called. It should have been,” Chief McManus said. “We don’t have any gaps in our policies, our protocols or our training that would have allowed that to happen. It was simply a failure on the scene by a sergeant who should have made that call.”

Ben Sifuentes, who is representing Officer Alejandro, said his client’s conduct was justified under Texas law. A lawyer cited in court documents as representing Sgt. Flores did not respond to calls and emails. Nico LaHood, representing Officer Villalobos, did not respond to calls, but The San Antonio Express-News reported that he said in a statement: “To charge these officers so quickly with murder in a situation like this is unprecedented,”

Local activists disagree that Ms. Perez died as a result of an isolated bad decision.

Edward Piña, the former president of the San Antonio branch of the A.C.L.U., said officers had told him on numerous occasions that calling in the Mental Health Unit was “not policing.”

“For as long as I’ve been practicing law, which is over 35 years, they’ve had a problem in dealing with persons that are exhibiting psychiatric symptoms,” he said. “Far too many of them wind up dead, either because of unlawful restraints or because they are, like Ms. Perez, killed when there is no justification for it.”

San Antonio formed its Mental Health Unit in 2008 with two officers and a sergeant. The unit now has 20 sworn members — 16 officers, two sergeants and two detectives. San Antonio has 2,516 police officers overall.

All officers in the Mental Health Unit undergo a crisis-intervention training program, which teaches them how to handle situations appropriately and reduce arrests of people experiencing a mental health crisis. In 2022, the unit responded to 5,201 calls. It has responded to around 2,000 calls so far this year, according to the San Antonio Police Department.

But, whether because officers decide not to call the unit or the unit fails to respond, those calls represent a small fraction of the total calls that make reference to mental health issues.

The police department received 54,932 mental health calls from January 2019 to April 2021, according to a 2021 report by the Meadows Mental Health Policy Institute, which issued a mixed assessment of the department’s record.

Although the department has officers trained in crisis intervention and a Mental Health Unit, “this is still fundamentally a law-enforcement-driven response without prevention, intervention and medically forward community connections to care,” the report stated. Even for officers trained in crisis intervention, it concluded, “their primary skill set remains law enforcement.”

Officers not in the Mental Health Unit are required to undergo 40 hours of crisis training to deal with individuals in distress. Additionally, over the next three years, the department is phasing in an advanced crisis intervention training course for its officers, Chief McManus said.

He acknowledged that there could be more members in the Mental Health Unit, but, he said, the response of those officers has been adequate.

San Antonio also has a year-old program that sends a mental health clinician and a paramedic — in addition to a police officer — to respond to mental health 911 calls made within its specific service area.

Officials say that Ms. Perez’s death should not define the department. Since its inception, the department has received national recognition for its work from organizations including the National Alliance on Mental Illness. The National League of Cities published a report about San Antonio’s Mental Health Unit, using it as an example for other cities to model and citing the success of its crisis response.

But Doug Beach, the executive director of the National Alliance on Mental Illness’s San Antonio affiliate, said the size of the Mental Health Unit was “frankly just not enough manpower” for a city this large.

He said his office received too many calls from families complaining of police responses.“Their family member may not have been shot and killed, but they’re not being treated or handled correctly, or they’re not getting the help they need,” he said.

Ms. Perez’s family has filed a lawsuit against the city and the three officers, saying officers could see she was experiencing a mental health crisis that night and that routine records checks by officers determined she had a history of mental illness and had been taken into protective police custody before. But a mental health officer was still not dispatched to the scene.

The lawsuit cites other cases in which, the suit asserts, San Antonio officers were sent to calls involving mental health concerns and the Mental Health Unit either was never summoned or did not respond. And it says that the entire response to Ms. Perez, particularly the failure to de-escalate a situation that did not require deadly force, reflects a department in need of systemic reform.

“Ms. Perez was not shot by a single officer who temporarily forgot his training in a split-second decision,” the lawsuit says. “There were multiple officers who acted over a two-hour period of time.”

Whatever the legal resolution, Ms. Perez’s family lives with the aftermath of that night. Her daughter, Alexis Tovar, a 24-year-old nursing student, said she remembers her mother as funny, outgoing and always willing to help others. She loved her mother’s cooking, especially her enchiladas, she said.

Ms. Tovar said she had not been able to eat or sleep since the shooting. She said she no longer saw the police as people who would protect her.

“It’s a nightmare that I don’t wish upon anyone,” she said. “I just pray that people don’t forget who my mom was because all I have left are the memories.”