A Pennsylvania woman who killed her much smaller boyfriend by crushing him to death has pleaded guilty to third degree murder.

Windi Thomas, 44, avoided a potentially longer prison sentence and other charges of assault and endangerment, for the murder of Keeno Butler, also 44, at their home in Eerie, Pennsylvania, in March of this year, according to GoErie.com.

'It's a good result based upon the facts of the case,' Thomas' court-appointed attorney, Mark Del Duca, told GoErie. 'I think it's fair for both sides.'

Windi Thomas, 44, pleaded guilty to 3rd degree murder in the suffocation death of her boyfriend

Her recommended sentence drops from 20 to 40 years in prison down to 18 to 36 years, as a result of the deal.

At the time of the murder, Thomas allegedly told police that she had been drinking and looking to purchase crack cocaine, Erie News Now reported.

It was then she got into the altercation with Keeno.

Thomas, weighing over 300 pounds, initially attacked her 120 pound boyfriend with a knife, stabbing him in the hand, before bludgeoning him with a table leg. It was then she smothered her victim by sitting on his chest.

Butler's death was ruled a homicide 'caused by respiratory insufficiency secondary to blunt force trauma to the neck and thoracic compression, exacerbated by blunt force trauma to the head,' according to the affidavit.

Keeno Butler died as a result of being beaten then crushed to death leaving behind a daughter and two grandchildren

Windi Thomas had a troubled relationship with Keeno according to Keeno's sister, Sandra Jean Butler

'I feel like she should have 40 or more,' the victim's sister, Sandra Jean Butler said in disagreeing with the deal. 'She deserved life.'

It was a troubled relationship, according to Sandra, in the two years that Windi and Keeno had been seeing each other.

'It was something that was going to happen,' the victim's sister told Erie News Now. 'They even stayed at my house and I asked her, 'don't kill my brother'.'

Keeno Butler is survived by a daughter, Adele Brown, two grandchildren, his mother and nine siblings including Sandra, according to his obituary in the Meadville Tribune.

Thomas is to be held in Erie County Prison to await sentencing.