Homeless woman accused of stabbing tourist inside NYC Macy’s bathroom was released from psych hospital morning of attack

The unhinged homeless woman accused of stabbing a tourist at Macy’s Herald Square had bought the knife she used in the store — and had once threatened to murder Sen. Elizabeth Warren, prosecutors revealed at her arraignment Friday.

Kerri Aherne, 43, was hit with charges of attempted murder, assault, and weapons possession in Manhattan Criminal Court for the savage attack that left a 38-year-old California mother riddled with stab wounds Thursday.

“She had purchased a knife at Macy’s and looked for someone to kill because voices in her head told her that she had to kill someone or else she would be killed,” Manhattan Assistant District Attorney Paul Barker told the court.

Aherne, who spent more than a year at Manhattan Psychiatric Center, was released from custody the same morning she carried out the vicious stabbing, prosecutors said.