That's partly because only three federal inmates have been executed in the United States since the federal death penalty was reinstated in 1988 after a 16-year moratorium. Those three are:
-- Timothy McVeigh
for the 1995 Oklahoma City bombing that killed 168 people. He was executed June 11, 2001.
-- Juan Raul Garza convicted of killing three people and running a marijuana drug ring in Texas. He was executed June 19, 2001.
-- Louis Jones for the kidnapping and murder of 19-year-old Army Pvt. Tracie McBride. He was executed March 18, 2003.
Before McVeigh's execution in 2001, the federal government had not put anyone to death since 1963.
Juries have handed down the death sentence in federal cases 74 times since 1988, according to the Federal Death Penalty Resource Counsel Project
In federal capital cases, juries choose death rather than life in prison about 30% of the time.
But when you take into account overturned convictions and vacated verdicts, the death sentence has only been applied 71 times in federal cases.
A trial judge has the power to vacate a jury's death sentence in federal cases, said Robert Dunham, executive director of the Death Penalty Information Center.
Such overturning of a death sentence occurs when a judge agrees with an attorney's post-trial motion to throw out the death penalty, Dunham said.
Three federal inmates who were sentenced to death died or committed suicide prior to the imposition of their sentence, the Federal Death Penalty Resource Counsel Project said.
There are about 60 people on federal death row and more than 3,000 on death rows across the country in state prisons.
Thirty-two states have a death penalty. Massachusetts is one of the 18 states without a death penalty. It was abolished there in 1984. In a Boston Globe poll taken in September, 57% of Boston respondents supported a life sentence for Tsarnaev, and 35% favored the death penalty.
According to Amnestyusa.org
, 139 countries around the world have abolished the penalty in law or practice. In 2009, the overwhelming majority of all known executions took place in five countries: China, Iran, Saudi Arabia, Iraq and the United States.