WEST PALM BEACH (CBSMiami) – A new lawsuit has been filed in the wake of the Jupiter Thanksgiving Day massacre where four people were killed including a six-year-old girl.

The parents of Paul Merhige have filed a counter-lawsuit against Jim and Muriel Sitton and Muriel’s father, Dr. Antoine Joseph.

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The Sittons and Dr. Joseph, filed suit first against Michael and Carole Merhige in September 2011 which claimed they knew their son Paul Merhige was unstable and potentially violent and did nothing to warn them that he would be attending their Thanksgiving dinner in 2009.

The lawsuit claimed the gunman’s parents were negligent because they knew their son was planning to attend the Thanksgiving event, even though he was unwanted and uninvited.

Tuesday, Merhige’s parents filed a lawsuit of their own which claims wrongful death and defamation.

In a statement released by attorney Allen Rossin, Michael and Carole Merhige only filed the counter-suit because, “Jim Sitton has chosen to make unfair and untrue statements about Michael and Carole Merhige which has added unnecessarily to their anguish and suffering.”

Michael and Carole Merhige claim Jim and Muriel Sitton and Dr. Antoine Joseph knew that Michael was going to attend the Thanksgiving dinner and that they were well aware of his mental health conditions, including any dangerous behavior.

In papers filed in Palm Beach County Circuit Court, the elder Merhige’s claim if the Sittons hadn’t allow Paul Merhige into their home, he wouldn’t have been able to open fire on the guests.

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In addition, Michael and Carole claim Dr. Antoine Joseph not only knew of Paul Merhige’s mental health conditions, as his uncle, but also had been his physician and treated him for a variety of medical conditions over the years.

They claim that prior to Thanksgiving 2009, Dr. Joseph had expressed his concerns to others that Paul Merhige may “hurt” someone and on one occasion refused to allow Paul Merhige to attend a family function at his home.

Michael and Carole Merhige also accuse Jim Sitton of defamation claiming they did not know Paul posed a danger to others and for repeatedly claiming they invited their son to the Thanksgiving dinner without telling other family members.

The night of the massacre, Merhige was having dinner in his cousin Muriel’s home when he got a gun from his car and opened fire at his relatives inside the house. He killed his twin sisters Carla and Lisa; who was pregnant, his aunt Raymonde Joseph, and 6-year-old cousin Makayla while she slept in her bed.

After a five-week manhunt, he was captured on January 2nd, 2010 on Long Key.

In October 2011, Merhige pleaded guilty to the murders. In return for his plea, he was sentenced to seven consecutive life sentences.

Tuesday afternoon, after learning about the countersuit, Jim and Muriel Sitton released a statement through their attorney David Prather which stated they are “outraged and devastated by the far flung allegations against them. The Sittons had not seen the killer for 13 years before he arrived on their doorstep, uninvited by them, but invited by his parents and with the knowledge of his sisters.”

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The statement continued, “The Sittons and Josephs were certainly aware that the Merhige’s were dysfunctional, but had no idea whatsoever as to the extent of that dysfunction or the depth of the killer’s mental illness. The Merighes however, were acutely aware of it.   While the Merighes are  certainly  grieving the loss of their family, sadly, they were the ones with the power to have prevented this unspeakable tragedy.  For them to now turn around and blame the Sittons and Dr. Joseph is the ultimate in adding the proverbial insult to injury.”