The prominent urologist accused of shooting upskirt video on the subway probably would have gotten off scot-free, were it not for an eagle-eyed former TSA employee. As we found out yesterday, Dr. Adam W. Levinson, an Assistant Professor in the Division of Robotics and Minimally Invasive Surgery at Mount Sinai, was arrested in the Union Square subway station during the evening rush hour. It turns out he got caught because one Sheldon Birthwright spotted him on the 4 train using a video camera disguised as a pen to capture upskirt footage.

“He’s leaning on the pole right next to the door,” Birthwright tells the Daily News. "He has a paper in his hand. But what’s mysterious about it, there’s a pen attached to the paper... He has it down in a very unsuspicious way. But every time the woman would move, he would move.” Levinson, who was wearing shorts (red flag right there!), allegedly followed the woman when she left the train at Union Square. Birthwright, a former TSA employee who now works in construction because he was presumably too freaking observant for the TSA, followed in hot pursuit.

“He walks directly behind her with the same paper and camera all the way up the stairs,” Birthwright tells the News. At the top of the stairs, the Good Samaritan spotted some cops and told them what he saw, but by the time they agreed to investigate, Levinson had vanished. But good old Birthwright found him on the L train platform, where he was allegedly standing at the bottom of the stairs, upskirt to his old tricks. Birthwright alerted transit police again, and this time they detained him without a struggle.

These video camera pens are easily obtainable for a modest price. Sources tell the News that investigators obtained a search warrant before viewing the videos captured by the pen, and found multiple victims recorded on it. Levinson was charged with unlawful surveillance in the second degree, a felony carrying a sentence of up to four years, and released on a $15,000 bond.

Mount Sinai has suspended Levinson pending the outcome of the investigation. "He's a doctor — it blows my mind," Birthwright tells DNAinfo. "At Mt. Sinai Hospital. It's horrible. A perversion. Nasty. Who knows what he was doing."