(NewsNation) — The suspect in a Buffalo, New York mass shooting — an 18-year-old man who targeted Black shoppers in a racist attack — was known to law enforcement but efforts to intervene fell short. In part, that’s because authorities are limited in what they can do before a crime has been committed.

Last year, when asked about his post-retirement plans in a high school economics class, the alleged shooter replied “murder-suicide,” according to the Associated Press.

That statement earned him a meeting with state police, who investigated the threat. After a mental health evaluation at a local hospital, investigators determined there were no immediate concerns and he was released.

He is now accused of opening fire and killing 10 people at a Tops grocery store Saturday, a location authorities say he chose due to its high concentration of Black patrons.

Despite the red flags, experts say law enforcement’s options are limited until certain thresholds are met.

“Until you have that act in furtherance, there is very little that law enforcement can do,” said Katherine Schweit, a retired FBI special agent who created the bureau’s active-shooter program.

In most cases, police have to wait before specific actions are taken, like acquiring a gun with intent to do harm or outlining a concrete plan, before they can charge someone with a crime, Schweit said.

But that process hinges on a key premise: it assumes investigators know when those actions have occurred. In many cases, they don’t.

Most of the time, authorities rely on tips from an informal network of parents, teachers, students, coaches and counselors. Researchers who study mass shootings say the decentralized approach can lead to information silos between agencies, which makes follow-through especially difficult.

“At the moment, it’s just individual agencies, individual officers, individual school teachers, a lot of them are just out there trying to figure this out on their own,” said James Densley, a co-founder of the Violence Project, a nonprofit research center that studies mass shootings.

That problem is compounded by the platforms potential mass shooters often use to communicate their intentions — social media sites and online forums.

“The amount of information that’s being loaded on a regular basis throughout all the sites on the internet cannot be possibly surfed by one agency,” Schweit said.

For that reason, prevention efforts have focused on strengthening those informal networks — implementing systems to ensure transparency and follow-up between community members.

Several states including Connecticut, Virginia and Illinois have passed laws requiring schools to develop threat assessment teams. As part of those teams, school counselors and coaches, among others, learn how to spot distress so they can intervene before it’s too late.

As recent cases have shown, empowering individuals to report concerning behavior can make a difference.

In September, two students were arrested after authorities said they were plotting a Columbine-style massacre at a Florida middle school. Three months later, police arrested a 19-year-old who they say planned to shoot people on his college campus in Daytona Beach, Florida.

In both instances, fellow students alerted authorities to the suspicious behavior.

In some cases, even the most minor interventions made a difference. As part of his research, Densley interviewed averted shooters — individuals who brought a gun to school with the intention of carrying out a mass killing but ultimately chose not to.

“It was a simple act of kindness, nine times out of 10, that got somebody out of that really terrible place that they were in,” Densley said.

But that’s also what makes the problem so difficult to solve. A solution that relies on strong interpersonal relationships is hard to scale and tough to legislate.

Even when intervention protocols are followed, tragedies can occur.

Nevertheless, building institutions that encourage peers and mentors to look out for each other could prevent the next mass shooting.

“I think it comes down to really being attuned to what’s going on in the lives of the people around us,” Densley said. “Let’s build those systems so that there is action that can divert people from that pathway to violence.”