Police have arrested a man caught taking photos inside the Callahan Tunnel.

According to investigators, the suspect claimed it was simple photography, but police are not taking any chances.

Massachusetts State Police said they found Muhammad Mamun taking photos inside the tunnel at 5 a.m. on Sunday.

"How could taking pictures put me in such a situation?" Mamun said. "People take pictures of Bunker Hill, they don’t get arrested. Why did I get arrested?"

Mamun, 25, said he is a medical student in Bangladesh currently working with a program at Mass. General Hospital.

Mamun said he decided to go to East Boston on Sunday morning to take photos of the skyline and thought he could walk through the tunnel to get there.

State Police said he walked by a "No Pedestrians" sign and they arrested him for trespassing.

"I’m not a terrorist," he said. "They can take everything, I have nothing to hide."

Police searched through Mamun’s phone and camera.

Mamun said he was planning on going home to Bangladesh on April 1.

Instead, a judge ordered that he remain in Boston until his next court date and put a GPS monitoring bracelet on his ankle.

"I’m a doctor, I’m a medical student," he said. "I have an ankle bracelet like any other convicted felons."

Mamun is due back in court next week.

He said the FBI has already talk to him. Court records show his case was forwarded to the Joint Terrorism Task Force.

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