Michael O'Neill has been jailed for 18 years on Wednesday for the murder of noted interior designer Stuart Rattle. O'Neill is also known as “The Talented Mr Ripley” for his constant lies.

According to Supreme Court Justice Elizabeth Hollingworth, O'Neill has been in a "fragile psychological state" when he killed Rattle, his partner of 16 years. The Supreme Court Justice concluded that it was O’Neill who murdered the 53-year-old interior designer in the heat of the moment after they had had an argument. Justice Hollingworth allowed no parole for O’Neill for 13 years.

The judge also said that, according to Rattle’s accounts, O’Neill was “lazy” and a “parasite.” Rattle apparently threatened him often that he would send O’Neill to where he belonged to. According to Justice Hollingworth, O'Neill was not treated as a partner but as an office boy. However, Rattle’s behaviour did not justify O’Neill’s decision to murder him.

"I accept you are genuinely remorseful for what you have done,” The Age quotes Justice Hollingworth speaking to O’Neill. “There is plenty of evidence that you are devastated."

The 48-year-old hit Rattle over the head with a saucepan at their South Yarra apartment at 6 a.m. on Dec. 4, 2013. Thereafter, he strangled him with a dog lead. According to O’Neill, Rattle called him a "frigid bitch" for refusing to have sex with him that morning. O'Neill kept the dead body inside a large furniture bag and left it on the bed. He then continued his normal routine over the weekend. He went back to the apartment on Sunday, Dec. 8 and set it on fire.

According to Chief Crown prosecutor Gavin Silbert, SC, O’Neill killed Rattle so that he could cover up his incompetence which had damaged the interior designer's business and put him on the brink of bankruptcy. O’Neill was responsible for accounts and quoting, invoicing and ordering stock for clients. However, defence barrister Ruth Shann argued that O’Neill had been enraged by the way the interior designer treated him.

O'Neill suffers from a dependent personality disorder. He lied to police for five hours before confessing that he had murdered Rattle. He belongs to a working-class family in Ireland. He emigrated to Australia when he was four.

Contact the writer: s.mukhopadhyay@IBTimes.com.au