Dr. Peter Nathan Steinmetz, a brain scientist with Barrow Neurological Institute in Phoenix, was arrested on Friday for mishandling his AR-15 in Phoenix Sky Harbor International Airport.

Steinmetz was possibly making a point about his Second Amendment rights, police theorize, when he bought a cup of coffee at Starbucks in Terminal Four with his rifle slung over his shoulder.

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It seems Steinmetz, a Tempe resident, was doing nothing wrong up until the moment he pointed the weapon inadvertently at two women in the "B"-gate waiting area. Police tell New Times that, in general, it's not illegal to carry a semiautomatic rifle into an airport terminal. In this case, the problem was "the way he was carrying it," says Phoenix police Sergeant Steve Martos.

After buying the coffee, Steinmetz walked to the east end of Terminal Four's third level and stopped in front of the B gates, in the "non-secure" part of the terminal.

He "then proceeded to remove the (Stag Arms) AR-15 from his right shoulder thus causing the muzzle to face two victims sitting to the right . . ." the booking sheet reads. "Both victims, a mother and her 17-year-old daughter, both stated they felt in fear of their safety when the rifle was pointed in their direction."

Steinmetz was taken into custody, arrested, and booked into the Maricopa County jail. Police are seeking two felony counts of disorderly conduct with a weapon.

Steinmetz pulled a similar stunt in November, when he showed up at Sky Harbor -- two days after a fatal shooting at Los Angeles International Airport -- with a rifle and his son, who also was armed. They told police they were there merely to pick up Steinmetz's wife from the airport, Martos says. No charges were filed in that incident.

Judging by his Barrow Neurological Institute web page, Steinmetz is a big deal in the world of brain science. He's been the principal investigator of the institute's "Neuroengineering/Human Neurophysiology Laboratory," also called the Brain Modeling Laboratory, since 2008. Steinmetz also has a personal website that lists his extensive work and research experience. His résumé lists his many awards and published works -- but says nothing about his apparent interest in gun-rights activism.

Carmelle Malkovich, Barrow spokeswoman, released the following statement from Dignity Health's St. Joseph's Hospital and Medical Center, where the Barrow institute is located:

"We can confirm that Peter Steinmetz is employed as a researcher with St. Joseph's Hospital and Medical Center. We are aware of the situation and are taking it very seriously. At present, this issue is being handled by human resources, and our policy is not to comment on HR matters."

UPDATE: Click the following link for an update on the arrest of Peter Steinmetz and a new response (sort of) from the Barrow Neurological Institute: Barrow Neurological Institute Purges Website of AR-15-Toting Doctor, Peter Steinmetz

UPDATE July 31: Peter Steinmetz, AR-15-Toting Barrow Scientist, to Hold News Conference on Monday

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