The news comes 63 years and one day after 9-year-old Carol Ann Dougherty was found murdered at St. Mark's Roman Catholic Church in Bristol in October 1962.
"We believe it may be the only rape and murder of a little girl in a church in the United States," Bucks County District Attorney Jennifer Schorn said at a news conference.
The Bucks County District Attorney's Office said Dougherty was raped and asphyxiated.
Officials revealed that their investigation has led them to their suspect, William Schrader, who has since died at the age of 63 in 2002.
Schrader, who was originally from Luzerne County, was a transplant to Bucks County at the time of the crime.
Through their investigation, officials said they were able to track Dougherty's travels throughout the community the day before she was murdered.
Officials say Dougherty, who was known to bike through town, was on her way to the library to meet her friends to get new books in a series she was reading.
Witnesses were able to tell police that she biked past a local market and even stopped at a café to grab a Coke and penny candy before continuing on her way.
However, she never made it to the library. Instead, her father found her dead in the church, located on Lincoln Avenue.
Officials said their suspect, Schrader, lived less than a five-minute walk from the church and had a disturbing history of violence towards little girls.
Investigators believed Schrader stayed in the area after the murder until January 1963, after he was interviewed by police.
Schrader came to the attention of the police after a neighbor near the church said he saw a suspicious stranger, identified as Schrader, the day of the murder.
Other witnesses alleged to have seen a man with a distinct facial scar, who "looked like he just committed a murder," officials said.
During his interview, Schrader allegedly lied to police and said he was working during the time of the crime, which officials said was not true, noting that Schrader had not shown up to work for three days straight at the time of the crime.
Schrader gave a pubic hair sample, but due to technical limitations at the time, no DNA was extracted.
In the decades since the murder, officials said they have been able to connect Schrader's sample to pubic hairs that were found clenched in Dougherty's hands when she was discovered.
Out of 141 samples analyzed during the investigation, officials said only Schrader's couldn't be eliminated.
Bucks Co. officials announce update in decades-old cold case murder of 9-year-old girl
A breakthrough in the case came last year when investigators interviewed Schrader's stepson, who said Schrader "confessed to him on two separate occasions that he murdered a little girl in a Pennsylvania church," the DA's office said. Schrader allegedly told his stepson he lured Carol Ann inside, raped her and "had to kill the girl in Bristol to keep her from talking," the DA's office said.
"On two separate occasions, William Schrader admitted to him that he had done this and got away with it. And they interviewed him, and he was consistent," said Schorn.
Carol Ann's sister says she wondered if she would ever see this day.
"Our family lived without answers and the uncertainty surrounding Carol's death became a part of who we were," said Kay Dougherty. "My parents both passed away without knowing on this earth who murdered their daughter. "After so many decades of unknowing, this finding finally brings closure and truth to a wound that never healed."
Authorities say Schrader fled the area and went on to sexually assault multiple other young girls, including family members. He also served time in prison after authorities say he set a home on fire, killing a child inside.
"Schrader's life was marked by a pattern of violence and sexual violence, particularly against young, pre-pubescent, and adolescent females," the DA's office said in a statement. Investigators determined he "sexually abused nearly every female child he lived with or had access to," prosecutors said.
Carol Ann is remembered as a bright young girl who loved to read and ride her bike. Now her sister says this brings a sense of closure that her parents didn't live to experience.
"Though nothing can bring Carol back, we can finally let her rest in peace," said Kay.
Authorities say this was a challenging case and that initially four different suspects were being considered.