For most of five decades, it seemed no one would ever be held accountable for the murder of a 7-year-old Illinois girl snatched off a small-town street corner as she played.

Now, someone has.

Fifty-five years after Maria Ridulph vanished, her friends and family let out a deafening cheer in court Friday as a judge pronounced a former neighborhood teen -- now a 72-year-old man -- guilty of the kidnapping and murder. It was one of the oldest unsolved crimes in the U.S. to make it to trial.

The roar of approval soon gave way to loud sobs from those who knew the little girl whose body was found after a five-month search that drew national media attention and haunted people across the country. Jack McCullough, who was 17-year-old John Tessier at the time, showed no hint of emotion.

"A weight has been lifted off my shoulders," said Kathy Chapman, 63, who was playing with Maria in the snow on the night of Dec. 3, 1957, before she vanished. "Maria finally has the justice she deserves."

McCullough approached the girls as they played and won Maria's trust by talking about dolls and giving her piggyback rides. At some point after Chapman ran home to grab mittens, authorities say McCullough dragged Maria into an alley, choked her with a wire, then stabbed her in her throat and chest.

The motive? Prosecutors say McCullough was sexually attracted to the second-grader. Even in a police interview in 2011, he recalled seeing Maria around the neighborhood, saying she was as pretty as a "Barbie doll." He wasn't charged with molesting her, however.

McCullough was briefly a suspect, like more than 100 others, in the 1950s, but he had an alibi. He told investigators he had been traveling to Chicago to get a medical exam before joining the Air Force. He settled in Seattle, working as a Washington state police officer.

As the months became years, many Sycamore residents assumed the killer must have been someone passing through town -- perhaps a truck driver.

A deathbed accusation by McCullough's mother in 1994 -- passed on to police by his half-sister in 2008 -- that she knew her son killed the girl led to a chain of events that brought about his conviction.

His mother, Eileen Tessier, had lied to police canvassing the neighborhood in 1957 about her son's whereabouts, buttressing his alibi, prosecutor Julie Trevartchen said Friday.

"She knew what she did and she didn't want to die with that on her conscience," she said.

McCullough's girlfriend in the 1950s also contacted police with evidence calling his alibi into question. She had found his unused train ticket to Chicago for the day Maria disappeared.