Weapons detection system Evolv Express' ability to detect large knives failed over half the time, according to the US National Center for Spectator Sports Safety and Security (NCS4).

A private report obtained via a Freedom of Information request by video surveillance research company IPVM revealed that Evolv’s ability to detect large knives scored just 1.3 out of 3. 

An earlier public report published by the NCS4 gave Evolv a score of 2.84 out of three, with many types of guns being detected 100 percent of the time.

In 24 walkthroughs, Evolv Express failed to detect large knives 42 percent of the time. The private report stated, “The system was incapable of detecting every knife on the sensitivity level observed during the exercise” and recommended full transparency to potential customers based on the data collected.

The findings raised questions about the accuracy and effectiveness of Evolv Express, and its manufacturer Evolv Technologies' transparency.