Brampton, Ont. — Peel Regional Police Chief Noel Catney Thursday termed it "a chilling thing," by which he meant the whole wretched sweep of the Cecilia Zhang story, but in particular the cruellest bit — that her alleged killer came first as friend, not foe.

"What shakes most of the investigators and myself as well," the chief told The Globe and Mail, his voice all anguish, "is, when is your kid safe? In bed, 3:30 in the morning, sleeping quietly, mere feet from you — and someone takes her from you?"

Min Chen, a bespectacled 21-year-old Chinese national who is in Canada on a student visa due to expire next month, was arrested at his Scarborough home two days ago and Thursday formally charged with first-degree murder in the death of the studious and gentle nine-year-old.

Mr. Chen's mother is a uniformed officer with the Shanghai police, The Globe has learned, his father an airline executive. His parents were generously financing his Canadian education, regularly sending money to a relative in Toronto, and believed their son was in school.

But Mr. Chen — who first enrolled at Seneca College and later at a little-known school for visa students — in recent months was neither attending classes nor working.

He had moved as a relative intimate among the small family, introduced to Ceci, as Sherry Xu and Raymond Zhang called their only child, by an older woman, about 10 years Mr. Chen's senior and also Chinese, who lived as a tenant in the Zhangs' Whitehorn Crescent house for six months while she attended the Seneca campus just minutes away.

This woman met Mr. Chen there, and while they were not romantically involved, they became friends such that the young man with the stick-'em-up haircut sometimes would drop by to see her, play games on her computer and occasionally stay for a barbecue.

Police will not identify the woman publicly because she will be a key witness at trial, but she moved out of the house in March last year. Mr. Chen visited her at the Xu-Zhang home at least four times, at least twice talking to the bright little girl, Chief Catney said Thursday at an enormous news conference at Peel Police headquarters.

When Cecilia's mother and father were told on Wednesday afternoon of the arrest, and heard Mr. Chen's name, they reeled in recognition. "They knew exactly who he was," Chief Catney said. "They did remember." "They had observed him on four occasions, seen him interact with their daughter. They were devastated, truly devastated."

As the chief said, "My understanding is, Cecilia knew him, he knew her. She would have been quite comfortable in his presence" on normal social occasions, "but on the night in question, I can't say."

Not for Chief Catney, a plainspoken man whose emotions Thursday ran perilously close to the surface, the usual dance of describing Mr. Chen as an "alleged" killer, for fear of tainting a potential jury pool — a precaution which, given the snail's pace of the Canadian criminal justice system is often unnecessary because by the time such a major case gets to trial, any prejudice to a jury pool is usually dissipated.

"This," the chief said at one point, setting down a large picture of Mr. Chen before the assembled cameras with a loud thump, "is not just a murderer. This is the most despicable of criminals. This is a child murderer."

 In his blunt words was a measure of the ripples of fear and abhorrence that spread far and wide after Cecelia's abduction in the early hours of last Oct. 20. Within days, Toronto Police, who were in charge of the original missing-child/abduction case, told the public that it did not appear to be a random attack by a stranger, but the logical alternative was equally awful — someone with knowledge of both this family and that house must have taken the child.

Indeed, it appears that was just what happened, though Chief Catney said police have not yet determined a possible motive. In his tender recitation of the night Cecilia was taken, the chief almost moaned aloud in despair.

"These parents were loving parents," he said. "They were mere feet away. If a child is ever going to be safe ..... if a child is ever to be safe, society and parents truly expect that will be within the confines of her bedroom."

In an effort to protect the integrity of the case they will take to court, the Peel chief and force remain close-mouthed about the evidence that the 32-member joint task force — composed of 14 Toronto investigators and 18 from Peel — has gathered while interviewing more than 50,000 people and logging 100,000-plus man hours in what Chief Catney counts as one of "the most exhaustive" probes in the country.

But The Globe has confirmed that investigators believe they have a strong circumstantial case and that physical evidence from the Mississauga ravine where Cecilia's remains were discovered on March 27 directly links Mr. Chen to the crime. The little girl, her body badly decomposed, was identified through dental records. Police have never revealed the cause of death.

There are also some indications that while Mr. Chen surfaced as a prime suspect only a month later, Toronto Police should have been able to trace him through their early interviews with tenants and former tenants of the Xu-Zhang house, but didn't.

Both Chief Catney and Toronto Chief Julian Fantino, who came in from leave for Thursday's press conference, lavishly praised the exceptional co-operation of the two forces, what Chief Fantino called the seamless transition of the case, and the working relationship between the lead officers, Peel Superintendent Frank Roselli and Toronto Detective-Sergeant Gerry Cashman.

Cecilia's parents had been renting out rooms in the house for extra income after moving to the pleasant North York neighbourhood so that their little girl, a gifted student and avid reader, could attend Seneca Hill Drive Public School, considered one of the city's finest, just a block or so away.

In total, 38 people, many of them Chinese, had rented rooms from the family, and Chief Catney said the case was investigated with "what I call front-line operational police work," with detectives interviewing each tenant or former tenant and asking who had visited them there.

More baldly, the chief said the investigation, which the Peel force led once Cecilia's body was found and the case was a homicide, went like this: "Here's the names; here's the people, get the hell out there and do it."

As of late April, Mr. Chen emerged as their suspect, and was put under intensive surveillance, the arrest prompted in part by the possibility that when his visa expired in August, he could leave the country and, once in China, Chief Catney said, "it would be nigh on impossible to get him back here."

The Peel chief said Mr. Chen was surprised when detectives came calling two days ago and made an uneventful arrest. "He did not expect us," he said.

Still in custody Thursday, but not charged, is an unidentified woman. Whether she will be charged with an offence is yet to be determined, and partly depends on whether she will co-operate with police and Crown attorneys.

She is another female friend of Mr. Chen, and The Globe has learned she may have played a role in the disposal of Cecilia's body, found behind the parking lot of Church of the Croatian Martyrs at Eglinton Avenue and Mississauga Road, in a heavily wooded area.

It is, Chief Catney said Thursday, an area Mr. Chen knew well, having gone fishing nearby. The young man's love of fishing is something he had in common with the little girl herself: Among the many pictures in her parents' empty home are some of her in a boat.

The task force has executed three search warrants — on Mr. Chen's home and 1994 Acura Integra car, now undergoing an extensive forensic investigation, and on the apartment of an associate.

Police cannot yet account for where the little girl was in the first 72 hours after her abduction, Chief Catney said, but The Globe has confirmed that detectives are certain her body was not in the Missisauga ravine in those early three days.

"Normally," Chief Catney said, "there is great joy when we resolve a case of this magnitude. "This case is an anomaly. I don't sense that joy, I personally don't feel joy. We're glad it's resolved, but when the purest form of innocence is violated, there's sadness, there's anger, there's regret. That's the mood I sense."

As Supt. Roselli, who still speaks with the burr of his native Scotland, said sorrowfully, "We cannot return Cecilia to her parents."

He praised Ms. Xu and Mr. Zhang for the compassion they summoned, even just minutes after learning that a young man they had welcomed in their home is charged in their daughter's death. Their instant recognition, Supt. Roselli said, "that this young man's life has also changed for the worse" was little short of magnificent.

"You really wish," his chief said later in a quiet moment, "that there was some way we could bring her back. We wouldn't have our arrest, but she'd be here, a lovely, pure, innocent, wee thing."