Scott McMillan was allegedly tortured by his mother, Jillian Tait, and her boyfriend, Gary Lee Fellenbaum. (AP Photo/Chester County District Attorney’s Office)

Inside a mobile home in West Caln, a Pennsylvania township some 40 miles from Philadelphia, 3-year-old Scott McMillan lived his last three days of life in torture.

Authorities said the boy’s mother and her boyfriend allegedly used a homemade whip, a curtain rod, an aluminum strip — even a frying pan — to beat him. They allegedly hung him upside down by his feet and whipped him. And when he couldn’t stand much more, they allegedly taped his arms and legs to a chair until he went limp.

The prosecutor called it “an American horror story.”

Jillian Tait, 31, and Gary Lee Fellenbaum, 23, were charged Thursday with Scott’s murder as well as aggravated assault for allegedly abusing his older brother.

Fellenbaum and Tait met recently while working at a local Wal-Mart. Last month, the two moved in together along with Tait’s 6- and 3-year-old sons as well as Fellenbaum’s estranged wife and 11-month-old daughter. All six lived in the trailer where, police said, Fellenbaum and Tait had been beating the boys for weeks.

Gary Lee Fellenbaum, left, and Jillian Tait, were charged Nov. 6, 2014, with the murder of Tait’s son, Scott McMillan. (AP Photo/Chester County District Attorney’s Office)

According to a criminal complaint, Fellenbaum told investigators he felt “disrespected” by 3-year-old Scott.

After the couple started living together, Fellenbaum allegedly started “disciplining” the boys. Prosecutors said he recently hung Scott and his older brother upside down from the back of a door and beat them as Tait looked on and laughed, according to police affidavits. Chester County District Attorney Thomas Hogan said Scott’s older brother knew better than to fight back, but Scott would struggle, which Fellenbaum and Tait thought was funny, the Associated Press reported.

Tait reportedly told investigators she participated in the abuse.

On Sunday, she told police, she and Fellenbaum began beating Scott. On Monday morning, Fellenbaum allegedly punched him in the stomach and the face for refusing to eat the toast they made him for breakfast. Then he allegedly threw the boy against a wall, the Philadelphia Inquirer reported. On Tuesday morning, his face was too swollen to eat — so he was allegedly beaten again.

The couple strapped Scott to a chair using electrical tape until he stopped squirming. When he became unresponsive, they stuck him in the shower for more than 30 minutes to wake him up and, when he wouldn’t recover, they laid him on an air mattress and left the home, investigators said.

When the couple returned from shopping and eating pizza, they engaged in sexual intercourse and took a nap, Tait reportedly told police. Neither one bothered to check on the child.

Police found no evidence that drugs or alcohol were a factor in the case.

“This is just evilness,” Hogan said. “It is an unspeakable act of depravity.”

Later Tuesday, Tait went to wake Scott and discovered he wasn’t breathing. She screamed for help and Fellenbaum’s 21-year-old wife, Amber Fellenbaum, dialed 911. When authorities arrived, they found an unresponsive toddler with bruises, puncture wounds and blood pouring from his nose and ears.

“Little Scotty McMillan is dead,” Hogan said.

Tait and Fellenbaum were arraigned Thursday. Authorities said they will seek the death penalty. The preliminary hearing is Nov. 14.

Amber Fellenbaum is charged with child endangerment because she allegedly witnessed the alleged abuse and didn’t try to stop it, Hogan said.

The Fellenbaums’ 11-month old girl was not hurt.

Tait’s 6-year-old son was taken a local hospital.

“It is going to take us years to put him back together again physically and mentally,” Hogan said.