The president of a construction trade group was found dead of a shotgun blast near National Airport yesterday morning, three days after the dismembered body of a Washington woman who lived in an apartment he rented was found in two rivers 44 miles apart.

U.S. Park police said Maurice Lee Mosier, 57, president of the National Constructors Association, a group of 50 engineering construction firms headquartered in Washington, drove to a remote road near the airport yesterday and apparently shot himself in the head with a 20-gauge shotgun. Park police said he was found by a motorist who got lost driving to the airport. Police said they also found ammunition, a rifle and a knife in Mosier's car.

Police said Mosier, of Arnold, Md., had been sought for questioning in connection with the slaying of 39-year-old Ernie Estelle Phillips of 905 Sixth St. SW. Parts of a body identified yesterday as Phillips were found over the weekend in the Patuxent and Choptank rivers in Maryland.

Prince George's police said Phillips lived in an apartment and drove a car listed in Mosier's name. Police said they were unsuccessful in reaching Mosier over the weekend. Mosier's coworkers said they believed he was vacationing in his son's cabin in Virginia over the weekend.

Jane Dudley, Mosier's secretary at the National Constructors Association, said she last saw him Tuesday and that he left the office at the end of the day not feeling well.

Police said they still had no motive or time of death in the slaying of Phillips. Identification came yesterday afternoon after the Maryland medical examiner's office checked her dental records.