Support for death penalty in US falls to 40-year low in new survey
Opponents of the death penalty hold signs in front of the Supreme Court in Washington, DC, on July 2, 2008. Photo by Nicholas Kamm for Agence France-Presse.

Support for the death penalty in the United States has fallen to its lowest level in 40 years, though most Americans still favor capital punishment for murder.

The finding came from a survey published Thursday, just days before the sentencing phase of the trial that will determine whether Boston bomber Dzhokhar Tsarnaev, 21, is sentenced to death or life in prison.

The Pew Research Center found 56 percent favor the death penalty for people convicted of murder, down six percent since 2011, while 38 percent are opposed.

The survey found that nearly two thirds, 63 percent, believe the death penalty is morally justified for a crime like murder. Just 31 percent said it is morally wrong even in cases of murder.

In 1996, 78 percent favored the death penalty and support for capital punishment was often above 70 percent throughout much of the 1980s and 1990s, the center said.

Much of the falling support comes from Democrats. Currently, 56 percent of Democrats are opposed to the death penalty. In 1996, Democrats favored capital punishment by 71 to 25 percent.

Pew said there had been less change among Republicans, 77 percent of respondents who identify with the more conservative party favor the death penalty down from 87 percent in 1996.

The survey was based on telephone interviews conducted with 1,500 adults across the United States between March 25-29. It carried an overall margin of error of 2.9 percent.

Twelve prisoners on death row have been executed in the United States so far this year.

Tsarnaev was convicted last week of carrying out the April 2013 bombings in Boston that killed three people and wounded 264 others.

Seventeen of his 30 convictions carry the death penalty under federal law. No one has been executed in Massachusetts since 1947.