Authorities say a Pennsylvania couple struck a 3-year-old boy with a frying pan, laughed as they hung him upside down and beat him, and eventually inflicted so many injuries that he died in what a prosecutor described as an "unspeakable act of depravity."

Jillian Tait, 31, and Gary Lee Fellenbaum, 23, were charged Thursday with murder in the death of Tait's son, Scott McMillan, and aggravated assault in the beating of his older brother.

Tait and Fellenbaum went car shopping, bought pizza and engaged in sexual activity as the boy lay dying Tuesday after weeks of escalating abuse that ended in three days of systematic torture, officials said.

Investigators found no evidence that drugs or alcohol were involved.

'Gary hung Scott and (his older brother) up by their feet one at a time and beat the boys while they were hanging upside down. Jillian stated that she and Gary were laughing during the incident.' - Police affidavit

"This is just evilness," said Chester County District Attorney Thomas Hogan said. "It is an unspeakable act of depravity."

The couple met working at Wal-Mart and last month moved in together, along with Fellenbaum's estranged wife. They lived with three children — Tait's 6- and 3-year-old sons and the Fellenbaums' 11-month-old daughter — in a mobile home park near Coatesville, about 55 kilometres northwest of Philadelphia.

The three adults told authorities that Scott McMillan had been whipped with a metal rod, punched and hit with blunt and sharp objects, and taped to a chair and beaten, police said in affidavits. The boy's dead body was covered in bruises, lacerations and puncture wounds.

Child Torture Death

Gary Lee Fellenbaum, left, and Jillian Tait, were charged with murder in the death of Tait's 3-year-old son, Scott McMillan. (Chester County District Attorney's Office/Associated Press)

"During one incident," the affidavits say, "Gary hung Scott and (his older brother) up by their feet one at a time and beat the boys while they were hanging upside down. Jillian stated that she and Gary were laughing during the incident."

Hogan called the case "an American horror story." He said late Thursday he had not yet been notified of the couple having obtained lawyers.

Fellenbaum's 21-year-old estranged wife, Amber Fellenbaum, was charged with child endangerment for allegedly failing to help the boy. She ultimately called 911 Tuesday night, authorities said. By then, Scott had been unresponsive for hours and had been put in a shower for more than 30 minutes by his mother and her boyfriend, investigators said.

Beaten for not eating breakfast

When the boy failed to awaken, they placed him on an uninflated air mattress and went shopping, authorities said. The couple returned with a pizza and, after eating, took a nap and engaged in sexual activity, according to Tait's statement to police. Tait said she then checked on Scott and yelled for someone to call 911 because he wasn't breathing.

Gary Fellenbaum severely beat the boy for refusing to eat toast both Monday and Tuesday morning, authorities said. The "discipline" included throwing him against a wall, knocking him off a chair with a punch and then taping him to the chair to keep him upright for more beatings, police said.

The couple allowed Scott's brother to hit him as well, according to the affidavit. But the older boy also showed signs of abuse, authorities said.

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

There was no evidence the infant was harmed, authorities said. She and the 6-year-old were placed in the custody of relatives, the prosecutor said.

Tait and Fellenbaum were being held without bail after their arraignments Thursday. They are scheduled for a preliminary hearing Nov. 14.

Amber Fellenbaum was being held on $500,000 bail. No attorney was listed in court records.