By Jessica Schneider, Geneva Sands and Katelyn Polantz, CNN

(CNN) -- Federal authorities would not have known earlier this summer that William Patrick Williams had threatened to "shoot up" a Lubbock, Texas, hotel where he was staying and had amassed weapons, ammunition and tactical gear were it not for Williams' grandmother.

In July, his grandmother alerted authorities after receiving a call from Williams who was both homicidal and suicidal, according to a criminal complaint against him.

Despite the threat he allegedly shared with his grandmother, Williams never acted, and he laid his arsenal out on the hotel bed when police visited him there.

So far, federal authorities have only alleged one crime against him: Giving an incorrect home address to a sporting goods store when he bought the AK-47 assault rifle. They're headed to court Wednesday morning about what whether he will be detained.

The case captures nearly every fraught situation that law enforcement may face in locating potential threats and preventing mass shootings, from the luck and diligence involved in finding possible shooters, to the narrow ways prosecutors can charge those who make threats.

Still, at nearly every level, government leaders say they're interested in ways to find future attackers and are encouraging the public to help them. But the tools authorities have are limited, and there's often no way to distinguish who may be an attacker and who is making an idle threat -- if authorities are even able to identify the potential actor.

A 2018 FBI-published study on mass shootings underscores the challenge for law enforcement. The study of 63 mass shooters in America over a 13-year period found that all displayed various "concerning behaviors" before they acted, and that when the behavior was seen by those close to each shooter, in many cases they did not approach law enforcement.

This week, following mass shootings in El Paso, Texas, and Dayton, Ohio, that killed 31, federal agencies announced their intentions to increase resources, partly to help build the grassroots efforts to identify shooters in advance.

Acting Homeland Security Secretary Kevin McAleenan told "CBS This Morning" Tuesday he wants to triple headquarters staff at his department who are focused on monitoring and trying to prevent domestic terrorism threats along with the FBI and Justice Department. The department has requested funds to expand the number of awareness briefings provided to law enforcement and community leaders as a way to build prevention efforts. DHS is also looking to place more mass murder-prevention specialists as regional coordinators in the field, a department spokesperson told CNN.

The department also requested from Congress more funding for violence prevention-related grants, but none of the additional money has yet come through. McAleenan said more investment was needed, "no question."

The FBI, for its part, announced Monday an intention to look into the now-deceased Dayton shooter's motives because of violent extremist beliefs he appears to have had about women.

"That has given us enough information to open an FBI investigation to make sure we have every single tool, every investigative capability to figure out why this happened and to try and make sure it doesn't happen again," FBI Special Agent in Charge Todd Wickerham said Tuesday. Since the shooting Sunday, authorities in Ohio led the response and investigation.

Local assistance

The FBI routinely provides assistance to departments across the country. The Bureau announced Tuesday it is opening a domestic terrorist investigation into the late July shooting at the Gilroy Garlic Festival outside San Francisco where a 19-year-old gunman killed three people and wounded 16 others.

"The feds have been fantastic partners for us," Captain Joseph Deras of the Gilroy Police Department said. "Even on the smallest thing they've been very responsive." The FBI will be looking into the gunman's target list that referenced religious institutions and political groups from both parties, as well as federal buildings and courthouses.

Gilroy's Police Department, like those in many smaller communities, doesn't have a full-time intelligence team dedicated to monitoring online threats. Instead, the department relies on officers from various divisions scrutinizing social media posts in their down time.

Just last week, a school resource officer flipping through Facebook noticed a string of disturbing comments from a 40-year-old local man. In one post, Jose Pinon of Gilroy referenced the Garlic festival shooting and added "my goal is to kill 500, not three," according to police.

The officer "took it upon himself to start digging, and he eventually went out and made the arrest," Deras said of the school resource officer who initiated the investigation. Jose Pinon was charged with making criminal threats, a felony. He is being held on bail after an initial appearance and has not entered a plea.

Despite last month's attack, Deras isn't sure though if the recent threats warrant a full-time analyst or team, and says he's largely satisfied with the work his officers are able to do part-time combined with assistance from the FBI. "Sometimes the workload doesn't mandate having a full-time team," Deras admits. Nonetheless, Deras says additional funding from the federal government could be useful for times when his officers are forced to dig deeper and go into the "realms of the dark web that might exceed our capability."

Still, many would-be violent extremists operate alone, or below the radar, often making it difficult to law enforcement to find them.

Larger departments, like in Pittsburgh and San Diego, typically employ their own threat assessment teams and participate in so-called intelligence fusion centers where threats and intelligence are analyzed by a cohesive unit. Despite the robust resources, top officials at these departments say constant communication with the FBI and Department of Homeland Security is key.

"My working relationship is about three to four times per week talking to the FBI," Pittsburgh PD Public Safety Director Wendell Hissrich said. "We work with the FBI to monitor social media sites, and when we have events our team is always looking at social media."

The grassroots and all-hands-on-deck approaches to law enforcement can only do so much, however.

Lone-wolf shooters are often unconnected to organizations like international terrorist groups, which federal authorities can more easily pursue to charge with crimes. And their extremist speech -- even if it's shared online and authorities track it -- is often protected under the Constitution. At the same time, a person's intentions aren't always obvious to relatives and friends, or a potential killer is masked from authorities through encryption online.

Adelia Johnson, who says she used to date the now-dead Dayton shooter Connor Betts, told CNN that Betts was fascinated by mass shootings. "He talked about it a lot. It was his main focus as a psychology person. He was interested in what makes terrible people do terrible things," she said.

Johnson said that on their first date, Betts showed her video of a mass shooting and Betts gave her a play-by-play of what was happening. But she felt it was not abnormal for a psychology student to be fascinated by the horrors of humans.

San Diego County Sheriff Bill Gore acknowledged the problematic nature of trying to track down lone wolves lurking online. "You can't be the thought police," Gore said. "That's the challenge, all of the freedom of religion and freedom of speech issues. They're problematic areas but they're not new to law enforcement."

After the shooting at the Tree of Life synagogue in Pittsburgh, Oren Segal of the Anti-Defamation League noticed an increase in law enforcement organizations tapping his group for training.

Segal encourages law enforcement to look for tips. He quoted the New York City Subway campaign for the public to "See something, say something" as an way for law enforcement to find potential killers. Authorities -- especially following the advent of ISIS -- sought to educate communities - including Muslim communities - about signs to watch for and how to report concerns to law enforcement.

"When it comes to actual law enforcement personnel, they want to get as much information as they can to protect their communities," he said Tuesday. "We have to know where the threats are coming from."

Gore says, for now, the appeal is to the public, and the private sector. "If we're really going to have an impact here it's going to require everybody," Gore said. "We've got to have the eyes and ears of the public. I think we need participation with tech companies and social media companies to help us with our efforts."