The man, who has not been identified, turned out to be a self-described "train enthusiast" who represented no danger, said 1st Sgt. Jonathan Green, a spokesman for the Maryland Transportation Authority Police, which assisted in the short-lived investigation.
Just after 8 a.m., the No. 419 train made its stop in the Odenton MARC Station just as the station was being checked by a Visible Intermodal Prevention and Response (VIPR) team, Green said.
Such teams were created under the Transportation Security Administration, part of the Department of Homeland Security, after a 2004 train bombing in Madrid. They are tasked with assisting other law enforcement agencies in patrolling the country's transportation network, including railways.
When the No. 419 train stopped, the conductor stepped off the train and told one of the VIPR team members that "there was a passenger on the train that many concerned riders pointed out as a suspicious person," Green said in an email.
The other passengers wanted the man, who was taking pictures of "the train, tracks, station and security cameras," taken off the train, Green said.
The VIPR team requested the man get off the train, and he "did so cooperatively," Green said.
The man then told the VIPR team he was a "train enthusiast" who enjoyed taking pictures of his daily commute to his job in Washington, Green said.
"The subject was very cooperative the entire time and offered to show the pictures he had taken," Green said. "No further action was taken and the subject was able to catch the next train to his destination."