By Rachel Leigh| April 3, 2012 at 3:12 PM EDT - Updated June 26 at 10:17 PM
WEST PALM BEACH, FL (WFLX) - A South Florida family says justice has not been served after a judge on Monday accepted a plea of not guilty by reason of insanity for Amy Kern, 33.
In February of 2009, Kern shot her aunt's boyfriend to death, then beat her own grandmother with a tire iron.
Relatives spoke to the judge Monday wearing shirts imprinted with the faces of Kern's victims. Kern cried as she listened. "I hope to God that she rots in hell. I mean it from the bottom of my heart," said Harriet Curles, the sister of victim William Chapman.
Three years ago, detective say Kern drove from Georgia to Port St. Lucie, where she stole her father's gun.
She used it to kill her aunt's boyfriend, Chapman, in Palm Beach Gardens. She then went to her grandmother Donna Kern's house in Jupiter and killed her with a tire iron.
Police found Kern afterwards, babbling about Jesus.
Her lawyer said Kern had been diagnosed as bipolar and schizophrenic in her 20s and had never gotten the proper psychiatric treatment she needed. "She was a young woman with hopes, dreams and a lot of potential," said defense attorney Nellie King.
But relatives of her victims said Kern -- who before her killing spree had been released from mental institutions in Georgia several times -- deserved to be called guilty and sentenced to prison.
Beverly Kern lost her mother and boyfriend to Kern's rage. "She can never be trusted on medication. She will always be a threat to society," said Beverly Kern.
Courts will decide whether she ever gets out of what the judge called a 'prison for the mentally insane.' "Please, as I requested earlier, don't lose track of this case. The stakes are high," said Beverly Kern.
Kern will be eligible for re-evaluations every six months to a year. "Every day I cry for my brother. Waiting three years for this day, hopefully we can have some closure now," said Curles.
The judge called the tragedy a failure of the mental health system.
On whether she will ever get out, prosecutors say, "You can never say never," but that the state attorney will be involved with all of her evaluations.