SALZHEMMENDORF, Germany — As a volunteer firefighter, Sascha D. was among the crew that rushed to the home of an immigrant family after it was firebombed in this small town in central Germany last summer.

But before he arrived, a court was told this month, Mr. D., 25, who is fond of late-night drinking and right-wing metal bands, and a friend, Dennis L., carefully made the Molotov cocktail themselves, using a pen to push wood shavings into the gasoline-filled bottle.

Mr. L., 31, who liked to daub swastikas on village walls, then hurled it through a window of the street-level apartment of a 34-year-old single mother of three from Zimbabwe who remains so traumatized she still has trouble sleeping, the court heard. German law protects the identity of the accused, meaning that unless there are extenuating circumstances, only first names and initials of surnames are made public.

“If the Negro burns, I will really celebrate,” Mr. L. said afterward, according to Saskia B., 24, who served as the driver for the two but is now testifying against her friends.