Molly and her father Tom Martens were both found guilty of second degree murder on Wednesday and sentenced to a minimum of 20 years in prison after killing the Limerick businessman with a brick and baseball bat in his North Carolina home.
Wayne and Catherine Fitzpatrick - the sister of Jason's first wife Mags, who tragically died from an asthma attack in 2006 - have spoken candidly today about his death.
Speaking on Sean O'Rourke on RTE Radio One, Wayne said: "The trial was extremely difficult for all of us and obviously the pictures that nobody else will see - pictures of his bedroom, the house, Jason himself and his autopsy, stuff that'll never get out of our heads, it's something that's still with me.
"It's hard to comprehend that they didn't just kill him, they slaughtered him, there were blows to his head after he died, that was proven to the State Pathologist.
You'd never expect that to happen to anyone, let alone my twin brother, you would never expect a wife and father-in-law to do that to anyone in any circ***tances whatsoever."
Catherine said that Molly made things difficult for the Corbett and Fitzpatrick families after his death, while she continued to try and get custody of the late couple's children Sarah and Jack.
She said: "She made everything difficult from the start, she didn't just murder them she caused a lot of hurt.
"After his death she even sent the bill for Jason's ambulance from the night he died to his parents."
Wayne added: "I remember when my sister Tracy, her husband David and a few friends went to North Carolina after Jason's death and Molly had his body moved to different funeral homes a few times.
"She wouldn't tell them where he was at first."