The warnings around Nikolas Cruz seemed to flash like neon signs: expelled from school, fighting with classmates, a fascination with weapons and hurting animals, disturbing images and comments posted to social media, previous mental health treatment.
In Florida, that wasn't enough for relatives, authorities or his schools to request a judicial order barring him from possessing guns.
Only five states have laws enabling family members, guardians or police to ask judges to temporarily strip gun rights from people who show warning signs of violence. Supporters of these measures, deemed "red flag laws" or gun-violence restraining orders, say they can save lives by stopping some shootings and suicides.
Florida, where Cruz is accused of using an AR-15 assault weapon to kill 17 people at his former high school, lacks such a law. He was able to legally own the semi-automatic rifle, even though his mother, classmates and teachers had at times described him as dangerous and threatening, and despite repeated police visits to his home.
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Red flag legislation has been introduced by Democratic state lawmakers, but it hasn't been heard during this year's session, and its fate is uncertain in a state Legislature controlled by Republicans who generally favor expanding gun rights.
After Wednesday's shooting, Republican Gov. Rick Scott said he will work to make sure people with mental illnesses don't have access to guns, but offered no specifics. Florida's GOP Sen. Marco Rubio — facing criticism from support he has received from the National Rifle Association — is going a step further now.
Rubio said on a Sunday morning show that state legislators should "absolutely" consider enacting a law enabling family members or law enforcement officials to ask a court to remove guns from a person who poses a danger. Rubio, who once served as Florida's House speaker, told Miami CBS affiliate WFOR that it's an "example of a state law" that could have helped prevent the Florida shooting.
In 2014, California became the first state to let family members ask a judge to remove firearms from a relative who appears to pose a threat. Its legislature took action after a mentally ill man, Elliot Rodger, killed six students and wounded 13 others near the University of California, Santa Barbara, before killing himself.
California's law also empowers police to petition for the protective orders, which can require authorities to remove firearms for up to one year. Connecticut, Indiana, Oregon and Washington also have some version of a red flag law.
More than a dozen others, including Hawaii, New Jersey and Missouri, are considering bills to enable family members or police to petition the courts to take weapons away from people showing signs of mental distress or violence.
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The Florida shooting has revived debate about whether teachers and school administrators should have that authority as well, given that people at Cruz's high school witnessed much of his erratic behavior.
California lawmakers voted to expand their law in 2016 so that high school and college personnel, co-workers and mental health professionals can seek the restraining orders, but Gov. Jerry Brown called the effort premature and vetoed it.
State Assemblyman Phil Ting, a San Francisco Democrat, said he plans to reintroduce the bill.
"We need to make sure that when people see signs, they have every ability to do something about getting guns out of the hands of mentally ill and dangerous people," Ting told The Associated Press.
Circumstances similar to those in Florida played out seven years ago in the shooting of Rep. Gabrielle Giffords in Arizona. Jared Loughner had become increasingly disruptive and erratic at his community college in the months leading up to the shooting, frightening students and causing teachers to request campus police officers be on hand during his classes. Eventually, the school threatened him with suspension.
Soon after, he went to a gun store and legally bought the weapon he used to attack Giffords as she met with constituents, shooting her in the head and killing six people.
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Without red flag laws, the main recourse available to family members is to have a troubled loved one committed to a psychiatric institution. Federal law permanently bans anyone who has been involuntary committed from owning guns, but such actions are more difficult to carry out than red flag laws, which are intended to be quick and temporary and have a lower standard of proof.
Without such a commitment, formal adjudication of serious mental illness or a felony conviction, many people can pass background checks and possess guns they already own.
The red flag laws act as a sort of timeout, so someone in psychological distress can get counseling while their fitness to possess a gun is evaluated, said Laura Cutilletta, legal director of the Giffords Law Center.
"It's a way to allow for temporary removal of firearms in a situation just like this: where somebody has made threats, where they have been expelled from school because of those threats, they're in counseling, and parents or the school or whoever it is understands that this person poses a threat," she said.
Many gun-rights activists oppose the laws. They say they can be used to unfairly take away rights from people who have not been convicted of crimes, nor professionally evaluated for mental illness.
The NRA's lobbying arm has said such laws enable courts to remove Second Amendment rights "based on third-party allegations and evidentiary standards" that are lower than what's required in criminal proceedings.
Connecticut led the way with a 1999 law, passed after an employee shot and killed four executives at state Lottery headquarters. It allows police to remove guns based on probable cause that a person poses a "risk of imminent personal injury."
In a study published last year, researchers at Duke, Yale, Connecticut and Virginia estimated that dozens of suicides have been prevented by the law, roughly one for every 10 gun seizures carried out. They said such laws "could significantly mitigate the risk" posed by the small number of legal gun owners who might suddenly pose a significant danger.
Associated Press writers Jonathan J. Cooper, Gary Fineout, Brendan Farrington and Lisa Marie Pane contributed to this report.