Current legislation has broadened the range of homicides subject to a charge of first degree murder and considerably extended the mandatory minimum time to be served before eligibility for parole consideration. As of June 1983, there were 1,800 prisoners defined as long term, those with a life or other indefinite term or with a definite sentence of at least 21 years. They comprised 16 percent of the total penitentiary population. Within the long-term group were 199 prisoners serving a sentence for first degree murder and 640 for second degree murder. Comparisons between the murderer population and other prisoners revealed few differences in age, racial origin, and language spoken. More first degree murderers, however, reported having a married or common law relationship of some continuity than any other prisoner groups. Approximately 62 percent of the first degree murder group and 78 percent of the second degree group had not been previously admitted to a Federal penitentiary, compared to 62 percent of those imprisoned for other offenses. Projection exercises have forecast a total murderer population ranging from 2,000 to 2,700 by the year 2001. A discussion of future directions for research and policy concludes the report. Tables, 33 footnotes, and a French version of the report are supplied.