Source 1
Guys wearing masks massacre people and steal money in front on everyone in the streets but no one alerts the police.
The mask copies the psycho pass of people around so the Dominator can't function because the coefficients are too low.
Kogami is the first to realize the trick and finds a way to get alone with the culprit. His own coefficient is the only one the helmet can reach so he can use his dominator to paralyze the other one and arrest him.
A guy with a helmet robs a pharmacy and kills the staff. No trace of weird psychopass when investigation starts.
After that a woman is beaten to death, people around don't react, the only way the police realizes there is a problem is because or the raising 'area stress'. As the investigation starts there too, robbery with a helmet again. Akane and the others separate in two groups, Akane's one chasing the guy who beat the woman to death (with a bat?)
Kogami and Dad reach the culprit, his helmet reflects Kogami's coeficient and they can fire with the dominator.
Makishima speaking with the robbers who try to steal the helmet from him. He tells them that they have no idea how foolish they are and beats them three.
Source 2
Shinya speculates that the helmet can copy the Psycho-Pass of surrounding people
When he pointed his Dominator at the helmeted guy, his Crime Coefficient read around 30.
After that, he asked Akane, "Inspector, what's your Crime Coefficient?", and confirmed that Akane and the helmet guy's Crime Coefficients were the same, thus figuring out the trick behind it, (or at least something like that because I only vaguely remember what happened).
It seems as though the helmet can copy Psycho-Passes within 30 meters, but if I recall from the avant-title of episode 1, the trigger must've been locked because the helmet was copying Makishima's Crime Coefficient, but when they exited the tower, the helmet must've copied Shinya's Crime Coefficient, allowing him to eliminate the guy. Sweet poison = stress levels are up
Makes sense, remember this helmet from 1 episode
