The body of a young man, whose legs were found Thursday morning dangling from a vent hood in the ceiling of a Dallas convenience store, appears to have suffocated while trying to enter the store from the roof, police said.The discovery was made by an employee of the Express Mart in the 7400 block of Harry Hines Boulevard, said Senior Cpl. Janice Crowther, police spokeswoman. The neighborhood is between Interstate 35E, also known as Stemmons Freeway, and Dallas Love Field airport in northwest Dallas."We know the lady closed the store at 10 o’clock last night, and then opened it again...