The Feb. 13 disappearance of Gerard Anthony Mack, an employee of the Maryland Port Authority in Dundalk, continues to baffle authorities.

"He was the kind of person who rarely missed work," said Ray C. Feldmann, a port authority spokesman. "This is very unusual behavior. He has been a good employee for 19 years. It is so out of character for us or his family not to hear from him."

Mr. Mack, who is employed as an engineering surveyor, has not been seen since about 8 p.m. Feb. 13. A truck belonging to him was found on a parking lot at Seagirt Marine Terminal with the keys in the ignition, officials said.

At the time of his disappearance, Mr. Mack was working on construction of a new building at Seagirt and operated out of a trailor that he shared with three other employees.

Police so far have no clues to Mr. Mack's disappearance.

Mr. Mack had a heart condition, but officials are even uncertain if that had anything to do with his disappearance.

"It's possible he had a heart attack and fell into the water, but we don't have any evidence to point to that," Mr. Feldmann said. "We can't rule out anything."