Nancy Grace Says Anna Kepner's Stepbrother Should Do Life Behind Bars

Nancy Grace is sick of Anna Kepner's family appearing to protect the stepbrother accused of raping and killing her ... and Nancy feels he should face life behind bars like every other killer.

Nancy popped in to "TMZ Live" absolutely furious about the case and the fact that the stepbrother -- identified in court docs as "T.H., a minor" -- is out on bond.

She told us, "I don't understand it. This is charged as murder one!"

She continued, "It seems to me, from the beginning, that the family has been more worried about protecting his identity and protecting him than they are about what happened to Anna and getting justice for her."

As you know ... Anna died on a cruise with her family back in November while she was sharing a room with her stepbrother.

Nancy pointed out the graphic image authorities painted of Anna's last moments, suggesting the last thing Anna ever saw was possibly T.H.'s face inches from hers as he allegedly strangled and raped her.

And Anna's then-boyfriend alleged T.H. had tried to sexually assault Anna before ... which Nancy says, puts the parents under a microscope for possible neglect.

Nancy said, "If they had been forewarned that this stepbrother had tried to assault her -- Anna -- in the past and done nothing ... why in the H-E-double-L did they put Anna in the room with the stepbrother?!"

As we reported, Anna's biological father, Christopher Kepner, shares Nancy's feelings that T.H. should've never been freed from custody. He told Daily Mail he wants to see T.H. in an "orange jumpsuit and handcuffs."