A dispute over a T-shirt has escalated into a legal battle between the Prince George's County police department and the county's police union, culminating in a $1 million federal lawsuit and an internal affairs investigation.

Last week, Cpl. Francis J. Mammano, a 13-year veteran of the force, filed a lawsuit in U.S. District Court in Greenbelt against county officials and Police Chief John S. Farrell, alleging that the police department violated his First Amendment rights by forcing him to remove a T-shirt that at least one other officer found offensive.

According to the lawsuit, the dispute began on Nov. 9, when Mammano showed up at police headquarters in Palmer Park for a day of target practice and in-service training. Attention soon focused on Mammano's wardrobe choice: a faded T-shirt depicting a scene from the Wild West, including a sketch of a gallows, two condemned men hanging from nooses and a bunch of cowboys standing around.

"Build it and they will come," the caption read.

The message on the T-shirt bothered at least one other officer, who complained to a lieutenant. The lieutenant, in turn, told Mammano to cover it up by buttoning his vest for the rest of the day. Mammano complied and went about his business, said John A. Bartlett Jr., president of the Prince George's chapter of the Fraternal Order of Police, which is backing Mammano in the case.

Later in the day, however, higher-ups in the police department decided to investigate further. A police captain called Mammano into his office and photographed the officer wearing the T-shirt. The captain then showed the picture to his superiors, who decided to confiscate the article of clothing, leaving Mammano "embarrassed and humiliated," according to the lawsuit.

Mammano is now under investigation by the department's internal affairs division for "conduct unbecoming an officer," Bartlett said. According to the lawsuit, Mammano is seeking $1 million in damages and an end to the investigation. He also wants his T-shirt back.

Lt. Andy Ellis, a police department spokesman, said he could not comment on the case because of the pending lawsuit.

Why, exactly, the T-shirt caused such a fuss is apparently a matter of interpretation.

According to the lawsuit, the shirt merely "contained a political statement affirming Officer Mammano's agreement with capital punishment." Mammano said he bought the T-shirt from Galls Inc., a Lexington, Ky., firm that sells supplies and novelty items to police officers and firefighters.

But police union officials acknowledged that rumors had spread throughout the department that the T-shirt had racial connotations, specifically that it may have resembled a lynching. Bartlett denied that, saying that even Farrell has agreed that the shirt was not racially offensive.

"There is nothing racial about it," Bartlett said. "This was his personal clothing which the police department has no right to take. What we want is for them not to violate his First Amendment rights."