EMBED >More News Videos A mother has pleaded guilty to third-degree murder in the beating death of her young son in Chester County.

EMBED >More News Videos Police say a man and his girlfriend are charged with murdering the girlfriend's 3-year-old son.

COATESVILLE, Pa. (WPVI) -- The Chester County mother of a 3-year-old boy tortured to death back in 2014, will spend at least four decades behind bars.Jillian Tait, who previously pleaded guilty to third degree murder, was sentenced to 42 to 94 years in prison for allowing her boyfriend to viciously beat Scotty McMillan and her older son for years.Prosecutors say, not only did Tait not stop Gary Fellenbaum from beating her sons, she sometimes helped.The child died after enduring a horrific beating inside the family's West Caln Township mobile home.On Tuesday, November 4, 2014, authorities were called to their residence for the report of an unresponsive child. Responding EMTs found 3-year-old Scott McMillan suffering from bruises, lacerations and puncture wounds all over his body.Police say Fellenbaum, Tait, and Fellenbaum's wife, Amber, confessed that the little boy had been beaten with blunt and sharp objects, whipped, taped to a chair with electrical tape and beaten, hung up by his feet and beaten, leading to his death.Authorities say they beat Scotty to death using homemade weapons, like a whip, a curtain rod, a frying pan, and an aluminum strip.Police say Tait explained that the fatal beating began when the boy wouldn't eat his breakfast.Chester County Prosecutor Tom Hogan said at the time that professionals with deep experience in these types of cases were brought to tears."Our ER nurses see a lot of terrible things. But when they saw his body, they wept," Hogan said.The district attorney says Gary Fellanbaum and Tait went car shopping, bought pizza, took a nap and engaged in sexual activity - all while the child lay dying after weeks of relentless torture.Tait allegedly told police that Fellenbaum beat her 6 and 3-year-old boys on a number of occasions. He would allegedly hit them with a closed fist in the head, face, chest and buttocks, and on one occasion she says he strung the boys up by their feet and beat them, while she and Fellenbaum laughed.Fellenbaum has already been sentenced to life plus 10 to 20 years.Scotty's brother now lives with relatives.----------