Evolv Technologies’ metal detection system under scrutiny

Following the recent Antioch High School shooting, MNPS installed Evolv Technologies concealed weapons scanners at the front doors of the school as a pilot program to assess how the technology works and the feasibility of implementing it district-wide.

But depending on how the technology is being used, there’s a chance it would not have detected the pistol in the Antioch High School shooter’s backpack. 

“Evolv is saying that it can automatically differentiate weapons from common objects — you know, it’s going to have this seamless, touchless experience,” Don Maye, head of operations at the security and surveillance research group IPVM, told the Banner. “But in reality, you either have to lower the sensitivity settings so low that weapons will go through, or you put it so high that most metal objects will alert it, and that really seems to defeat the value proposition of Evolv.”

Evolv’s concealed weapons scanners detect ferrous metals — metals containing iron as the main component. However, unlike a traditional metal detector, the sensors are supposed to distinguish between weapons and harmless everyday items instead of alerting when they detect metal. Unlike traditional metal detectors, which require people to file through one by one, emptying their pockets and bags of any metal items, Evolv scanners are meant to allow large numbers of people to quickly enter through security checkpoints without having to discard harmless metal objects.

However, using the sensors is not as simple as installing them. 

Evolv sensors have sensitivity settings ranging from A to G. According to a since-deleted Evolv presentation obtained by IPVM, at sensitivity settings A or B, the sensors would detect a trigger bomb or an AR-15 but could miss anything from a knife to a pistol. At the highest sensitivity, the system would detect even a small knife but would also be set off by just about any harmless piece of metal. 

“For safety and security reasons, I’m not going to get into the specific settings on our security equipment,” MNPS spokesperson Sean Braisted said in an email to the Banner. “We are currently able to process students with about 4 staff members per lane, and there are four lanes in total in the building. … The system flags potentially suspect items for secondary screening, at a rate of about 9-20%, but the secondary screening has not resulted in any weapons being found. Typical items that need further review include laptops, ipads, umbrellas, eyeglass cases, and binders.”

The full statement from Braisted can be found at the bottom of this story. 

When the company first went public in 2021, it was widely marketed towards stadiums and is currently installed in Nissan Stadium. However, while it may work well at Nissan Stadium, a school security environment is far more challenging.

“The people going into sports stadiums are already conditioned not to bring in certain metal objects, whereas, in school districts, students are bringing in water bottles, calculators, three-ring binders, all these other objects that typically aren’t going to be in sports stadiums,” Maye said. 

This leaves schools with a difficult choice: either turn the sensitivity low so that there are fewer false alarms but weapons, such as the pistol that was in the Antioch High School shooter’s backpack, can get through, or turn the sensitivity high enough that they will be alerted by most metal objects, which requires more security staff to do secondary screenings.  

Massaging the Message

When Evolv first went public, it drew the attention of the Federal Trade Commission over its claims of creating a “weapons-free environment.” The company settled with the FTC in November, banning it from misrepresenting the abilities of the technology. 

“The technology should be getting better, obviously, over the years, but instead, you’re seeing the marketing claims being whittled down,” Maye said. “So it’s kind of like the opposite of what you would expect with technology. You would expect that as technology improves, you’d be able to have stronger and stronger claims to support what your technology can do. In this case, you’ve seen a regression in the claims.”

But that wasn’t Evolv’s only controversy since going public: An ongoing lawsuit in New York alleges Evolv scanners missed a knife that was used in a stabbing; The Securities and Exchange Commission continues an ongoing non-public investigation into the company; Shareholders have brought an ongoing class-action securities lawsuit; The company fired its CEO in October amid a sales misconduct investigation, and the CFO resigned in November. 

“This is highly atypical in my experience covering and seeing the landscape of physical security technology companies publicly traded,” Maye said. “There are certainly other companies that have had issues like this. But it’s still kind of an outlier relative to the broader industry.”

The scanners aren’t cheap either. While a traditional metal detector might cost $5,000-$10,000, Evolv scanners are reportedly among the most expensive security systems, at $2,500 to $3,000 per month over a four-year lease, not to mention staff. 

“Schools are an attractive market for security technology for a couple of reasons,” Maye said. “There’s money there, and the reason why there’s money there is that there’s violence happening there that the public is concerned about.”

The full statement from Metro Nashville Public Schools Chief of Communications and Technology:

For safety and security reasons, I’m not going to get into the specific settings on our security equipment.

We’ve been monitoring the flow of traffic for the school throughout last week and this week to make process improvements as it relates to the flow of students. We are currently able to process students with about 4 staff members per lane, and there are four lanes in total in the building. We were able to get students into the building each morning prior to the first bell at 7:15 a.m., without problems. Most students are headed to pick up breakfast or go to their classrooms before 7:05 a.m.

The system flags potentially suspect items for secondary screening, at a rate of about 9-20%, but the secondary screening has not resulted in any weapons being found. Typical items that need further review include laptops, ipads, umbrellas, eyeglass cases, and binders. We have signs up encouraging students to take them out and place them on the table prior to entering the scanner, resulting in fewer alerts as more students learn the process.

We understood this would be required when adopting the system and notified students and families in advance of this reality. Using a traditional metal detector system where every bag would have to be individually searched would likely result in significantly longer delays.  

We’ll continue to educate students on what items to take out of their bags prior to screening to further reduce alerts.

Related