Democratic presidential hopeful Hillary Clinton defended her support for the death penalty by citing several infamous mass murders during MSNBC's Democratic Presidential Candidates Forum on Friday.

Clinton said cases like the June murders of black churchgoers in Charleston, South Carolina, should prompt "a legitimate discussion" about the death penalty. But she argued there are now "too many cases put into the capital offense category."

In October, Clinton said she doesn't support abolishing the death penalty, but wants it reserved for "very limited and rare" cases. During the forum on Friday, Clinton said she was commenting on the federal death penalty system. She named Boston Marathon bomber Dzhokhar Tsarnaev, 9/11 mastermind Khalid Sheikh Mohammed and Oklahoma City bomber Timothy McVeigh -- people who committed what she called "really heinous crimes" -- as those who "should potentially have the death penalty."

Clinton also doubled down on her earlier statements that the death penalty is often administered in a discriminatory way, and argued states should "take a really hard look" at their capital punishment laws, because some "have gone way too far."