NEW YORK » Long before Erika Menendez was charged with pushing a stranger to his death under an oncoming train at a Queens elevated station, she had years of contact with the city’s mental health and law enforcement establishments.

Menendez, 31, was treated by the psychiatric staffs of at least two city hospitals, and caseworkers visited her family home in Queens to provide further help. She was also arrested at least three times, according to the police, twice after violent confrontations.

Her years of inner and outer turmoil culminated in the deadly assault on an unsuspecting man who was waiting for a train Thursday. Beyond stirring fear among riders on crowded platforms across the city, the attack also raised new questions about the safeguards in a patchwork private and public mental health system that is supposed to allow mentally ill people to live as freely as possible in the community while protecting them and the public.

A similar attack more than a decade ago led to a law aimed at forcing mentally ill people with a history of violence to undergo treatment, but it is widely acknowledged to cover only a small portion of those who need help.

D.J. Jaffe, the executive director of the Mental Illness Policy Organization, an advocacy group, said that thousands of troubled individuals with violent histories were released from mental health facilities and, beyond requiring that they have a home to go to and an outpatient care plan in place, there is little oversight of their activities.

"No one monitors if they are taking their medication," he said. "Or follows up to see if they are a danger to themselves or others."

Menendez’s case puts renewed attention on a mental health system that is a loose amalgam of hospitals, supported housing, shelters and other advocacy and support groups, in which mentally ill people often bounce from one to the other and ultimately fall through the cracks. It is not known precisely where Menendez fit in.

City officials said it would be misleading to conclude that anyone was at fault in her treatment.

"People get well and then they get sick again," Ana Marengo, a spokeswoman for the city’s Health and Hospitals Corp., which runs Bellevue and Elmhurst Hospital Centers, said Sunday. Menendez had been treated at both hospitals, according to friends and law enforcement officials.

Marengo declined to confirm or deny whether Menendez had been treated at either hospital, citing confidentiality rules, but said that patients who were treated at city hospitals often were discharged into the care of outpatient mental health providers.

The fragility of the system could be seen in the aftermath of Hurricane Sandy, when Bellevue Hospital Center, a public hospital that treats many of the city’s most seriously ill patients, was forced to evacuate and close.

Although someone familiar with her case said Menendez had been treated at Bellevue several months before the storm, Marengo said that her case "has absolutely no relation to the closing of Bellevue." She added, "All patients evacuated from Bellevue were transferred to other hospitals and received the services they needed without interruption, and all potential Bellevue patients have been referred to other hospitals for care."

Still, there were ample warnings over the years concerning Menendez.

In 2003, according to the police, she attacked a stranger, Daniel Conlisk, a retired firefighter, as he took out his garbage in Queens.

"I was covered with blood," Conlisk recalled Sunday. "She was screaming the whole time."

Just two months earlier, Menendez was accused of hitting and scratching another man in Queens. She was also arrested on suspicion of cocaine possession the same year.

Since then, according to friends and people familiar with her record, she has been cared for at mental health facilities in Manhattan and Queens as her problems worsened.

Between 2005 and February 2012, the police responded five times to calls from family members reporting difficulties in dealing with Menendez, reportedly stemming from her failure to take certain medication, according to a law enforcement official. In one of these instances, in 2010, she threw a radio at one of the responding officers, the official said.

"She has been in and out of institutions," another law enforcement official said, speaking on the condition of anonymity.

Within the past year, she was discharged from Bellevue, according to a person with knowledge of her medical history.

An attendant at the psychiatric ward at Elmhurst Hospital Center declined to go into detail about Menendez’s treatment there, but said, "All I can tell you is we know her very well."

Menendez is being charged with murder as a hate crime and, if convicted, faces a possible sentence of life in prison.

For prosecutors, the decision to charge her with a hate crime was based on statements she gave to the police after her arrest Saturday, when she said she attacked the victim because she hated Muslims and Hindus.

A family friend who identified himself only as Mike insisted that Menendez is not a racist, but acknowledged her troubled mental history. He said that she was supposed to be monitored as part of an outpatient program for the mentally ill run by Elmhurst.

"We had someone come to the house, spend six minutes, asked how she was doing, giving medication," he said by telephone. "I used to tell them, ‘Listen, she’s not home.’ And then they would come back the next week. They’d leave you the medication and come back in the next week."

The exact nature of what Menendez was being treated for could not be confirmed. It was also unclear if she was currently on medication or had lapsed in her treatment.

When she was arraigned Saturday night, the judge ordered that she be held without bail and undergo a psychiatric evaluation.

It was the second time in less than a month that a commuter was pushed to his death at a New York City subway station.

In the first case, Ki-Suck Han, 58, of Elmhurst, Queens, died under the Q train at the 49th Street and Seventh Avenue station Dec. 3. Naeem Davis, 30, was charged with second-degree murder in that case.

Both attacks bear a striking similarity to an attack that occurred in 1999 and galvanized the city.

That January, Andrew Goldstein pushed Kendra Webdale, 32, into the path of an N train at the 23rd Street station, killing her.

He was convicted of second-degree murder, a decision that was overturned. But he ultimately pleaded guilty to manslaughter. Although he stopped taking medication for schizophrenia, the insanity defense did not convince a jury.

Yet after Webdale’s death, the state Legislature passed Kendra’s Law, which allows judges to order closely supervised outpatient treatment for mentally ill patients who had a history of refusing to take their medication and who had been put in jail or hospitalized repeatedly or become violent.

The latest attacks show the flaws in the system, according to some advocates for the mentally ill.

"If you are involuntarily committed, once you are no longer dangerous, you are discharged," Jaffe said.

Menendez often stayed in Rego Park, Queens, with her mother and stepfather in their 14-story apartment building. That was the address where family friends said she was visited by outpatient mental health workers from Elmhurst hospital.

When she was arrested in 2003, she was staying in Ridgewood, Queens.

In an interview, Conlisk, now 65, said he had never seen her before the confrontation.

He said she approached him from behind, screaming and accusing him of sleeping with her mother.

"She goes into a boxer’s stance and then she punches my face," he said. He pressed charges and had a restraining order against her for a year, he added, but never saw her again.

"I think I would have been dead if she had a weapon," he said.