But he stuck to the same alibi he gave when first questioned by investigators more than half a century ago, when he was 18: that he could not have committed the murder because he had traveled to Chicago that day for military medical exams before enlisting in the Air Force.
"I have an iron-clad alibi," he said. "I did not commit a murder."
McCullough, then known as John Tessier, lived near the girl and matched the description of the suspect given by Ridulph's 8-year-old friend, Cathy Sigman, who last saw her on Dec. 3, 1957, at about 6 p.m. Sigman said she left Maria with a young man and ran home to get some mittens; when she returned 15 minutes later, the two were gone.
Thousands of people joined in the search for the missing girl, and many kept their own children locked indoors lest they be nabbed next. Maria's remains were found the following April, about 120 miles away.
McCullough was arrested in Seattle last week after investigators said new evidence undermined his alibi. He's being held in the King County Jail on a fugitive charge pending his return to Illinois.
According to a police affidavit in the case, last year, McCullough's high school girlfriend discovered his train ticket to Chicago behind a framed photograph of them -- and it was unused. Detectives wrote that when he was questioned in 1957, he claimed he had traveled to Chicago by train.
Though Sigman said she was never asked to identify McCullough as the suspect at the time, she picked his photo out of a montage detectives showed her last September, the affidavit said.
The affidavit also alleged that McCullough has a history of molesting girls. One young witness told agents in 1957 that he had sexually abused her on numerous occasions, and in the early 1980s he lost his job with the Milton police department in Washington state after he was accused of having sexual abuse with a runaway in her early teens. He pleaded guilty in 1983 to unlawfully communicating with a minor.
McCullough declined to discuss those topics with the AP.
"Don't go there. What I did or didn't do in my private life that would make me look bad, so what?" he said. "I didn't commit a murder, and that's all I'm charged with."
The white-haired, white-mustachioed McCullough spoke with the AP by telephone receiver through a glass partition, wearing a bright red jail uniform, and began the interview by pressing against the glass a crinkled piece of white paper on which he had scrawled letters and words in various alphabets -- by which he meant to demonstrate that he wasn't an idiot, he said. He developed a love of studying other languages and alphabets while in the military, and maintains the hobby as a vehicle for learning about history, he said: He's currently studying the ancient script of cuneiform and said he has recently started praying to the ancient god of the Persians, Ahuramazda.
He suggested that he himself might have prompted agents to reopen the investigation. He called the FBI a few years ago, he claimed, after a dream prompted his recollection of a slightly older boy who had lived in the neighborhood at the time. The boy, named Brooks, had been taken in by a family named Davies, McCullough said, and Brooks would have also matched the suspect's description.
"I called the FBI," McCullough said. "They said thank you. And here I am."
Those details could not immediately be verified.
McCullough said he didn't remember every detail of what he told the FBI in 1957, but he said there's a good reason his train ticket was unused: He never used it.
He says his stepfather gave him a ride to Chicago, and after a long day of physical and psychological tests, he hitched a ride with someone he'd just met to Rockford. From Rockford, a drive of more than 40 miles from Sycamore, he called home to ask his stepfather to come pick him up.
Investigators wrote in the affidavit that they have verified that a collect call was made from a Rockford pay phone to McCullough's childhood home that night, lasting from 6:57 to 6:59 p.m. If he made that call, he said, "How am I involved in a kidnapping at 6 p.m. in Sycamore? A fifth-grader can figure this out."
Rockford is roughly on the way from Sycamore to where the girl's body was eventually discovered, in far northwestern Illinois.
McCullough said he didn't believe investigators had ever tried to verify that he was in Chicago that day for medical tests -- and records of that day should still exist at the National Archives repository of military personnel records in St. Louis, he said.
"St. Louis will have records of everything," he said. "If somebody would go there, it would exonerate me."
A clerk at the repository told The Associated Press Friday that no records could be made public without McCullough's signed permission. She said law enforcement authorities are allowed access to the records without a person's authorization.
It wasn't immediately clear whether the records do in fact still exist. A fire at the archives in 1973 destroyed millions of military personnel records -- including about 75 percent of records of Air Force personnel discharged between 1947 and 1964 whose names last names came alphabetically after H. McCullough left the Air Force in 1960.
McCullough was born in Belfast, Ireland, in 1939, and said he moved with his mother to England when she took a position as a searchlight operator with the Royal Air Force, once lighting up a Nazi plane during a bombing raid. His father left when he was 3 -- his mother claimed he was killed in the war, but McCullough always suspected that he simply left the family.
McCullough and his mother came to the U.S. in 1946 and settled in Sycamore, where he lived until he was 18, he said. He said the town was a lot like the television show "Happy Days" when he was growing up.
McCullough said he served four years in the Air Force followed by 10 in the Army, including a stint in Vietnam for which he said he was awarded a Bronze Star. He then settled in Washington state, where he worked as a police officer and security guard and started a company driving pilots between hotels and Seattle-Tacoma International Airport. He married three times, the last time to his current wife in 1994. It was then that he changed his name from Tessier, his stepfather's name, to McCullough, his mother's maiden name.
He had been living with his wife at a North Seattle retirement home, where he worked as a night watchman, when he was arrested. Residents there describe him as pleasant and helpful.
"If I'd have done this, how could I have possibly lived with myself?" he said. "That had to have been an emotional trauma."
McCullough maintained that he doesn't know how his high school sweetheart wound up with the unused train ticket -- but learning of its curious discovery behind the photograph tickled him. The couple broke up when he left to join the Air Force.
"She doesn't know it, but I loved her for decades," he said. "She got married and I put it aside and said, `Eh, give up.'
"But she keeps a picture of me and her for 50 years. Imagine that."