Russell Williams is now an admitted double murderer, rapist and sexual fetishist, but it's the scale of his obsession, the depth of his deviance and his utter relentlessness which is so terrifying.
Others have killed more, raped more, victimized more.
But in Canadian criminal history, probably no one ever before has done the devil's work with such single-minded purpose and documented his exploits with such devotion.
Of the thousands and thousands of pictures the police recovered from Colonel Williams's computer, a tiny sampling of which are being shown in court, the ones which best tell the tale of what made him tick are as follows.
There are usually one or two of these, or a variation, in every set from every one of the 48 houses he broke into in the nearby town of Tweed and Ottawa, where Col. Williams and his wife Mary Elizabeth Harriman had a cottage and home respectively.
In these photographs, Col. Williams is always naked but for the stolen women's panties (and all too often the stolen cartoon character-decorated underwear of the young girls he really favoured), striking a pose before a mirror in one or another of the houses he has invaded, and he is taking a picture of himself (the camera sometimes visible in the photograph) watching himself masturbate.
It is the ultimate snapshot of sexual self-gratification: Col. Williams photographing himself watching himself in a mirror as he touched himself.
Well, come to think of it, maybe not - in his day-long appearance at Ontario Superior Court here Monday, the 47-year-old former commander of CFB Trenton could not help himself, and turned his head up and to the side ever so slightly whenever these particular kinds of pictures were displayed on the big monitors.
If these quick sidelong glances didn't put the lie to the posture of downcast criminal he adopted in the prisoner's box, they spoke at least to the grip of his obsession.
He formally pleaded guilty to 82 break and enters, two sexual assaults and two forcible confinements and two counts of first-degree murder in the deaths of 38-year-old Corporal Marie-France Comeau, who was under his command, and 27-year-old Jessica Lloyd, a civilian who worked for a local bus company, just as his lawyer Michael Edelson promised he would earlier this month.
From the agreed statement of facts, only partly read into the record thus far, Col. Williams's stated age preference in these forays was for intimate clothing worn by women ranging from their late teens to early 30s.
But as Crown prosecutor Robert Morrison once noted, his voice frequently dripping with contempt, in 13 of the 48 homes Col. Williams invaded, "females under the age of 18," several as young as 12, were the primary targets.
With the younger girls' clothing, Col. Williams often posed in their bedrooms, surrounded by dolls, toys and stuffed animals. He once appeared to be masturbating next to a large white stuffed bear; in another photograph, he wore a pair of girls' Tweety Bird underpants and, in a third, was fondling himself while dressed in a girl's white skirt.
Yet perhaps the most egregious incident of this sort, because of the monstrous betrayal of trust it represented, was his very first break-in, when he invaded the home of neighbours in Tweed who considered him and his wife friends and had hosted them for dinner many times.
Col. Williams had taken the couple's then-12-year-old daughter and her sibling out tubing on a nearby lake and she, on six occasions, had looked after Col. Williams's beloved cat, Curio, and even had a key to their home.
His thank you was to steal her underwear, then pose on her bed and ejaculate to climax underneath dog pictures.
He broke into that home on three different occasions, and the family never noticed anything awry. Only 17 of the robbed homeowners ever did, with the 31 others never suspecting someone had been in their houses.
These thousands of break-in pictures, Mr. Morrison told Mr. Justice Robert Scott, "are invaluable in explaining Williams's makeup - his unusual sexuality, gradually escalating risk-taking" which culminated in him videoing "Ms. Comeau and Ms. Lloyd and their violations."
That risk-taking was steadily growing, evident first in his leaving signs that he or someone had been in a house (he would rearrange things slightly), then in his greed (he would steal all or most of a woman's underwear, 68 pieces here, 186 pieces of clothing there), then in outright clues (a computer message saying "Merci" for one woman, whose underwear and sex toys he'd stolen).
By the summer of 2009, Col. Williams was occasionally breaking into homes stark naked, watching targets from their own backyards, and once stealing a pair of panties from a woman he had watched jump into the shower.
Not only did he take pictures of himself in the stolen gear, but he also took further pictures, probably tens of thousands, of his prizes. He photographed them as collections, and as individual pieces, all downloaded into files on hard drives he kept in the Ottawa home.
Many times, he photographed these stolen items at the Ottawa home, whiling away Saturday mornings.
He broke into homes, or worked on his collections, not only in the wee hours but also in broad daylight, last thing at night, first thing in the morning, after work and before.
In 2008, the day after Remembrance Day, he broke into an Ottawa home; he celebrated New Year's Eve that same year breaking into another house, focusing on the 15-year-old daughter's clothing, and on his computer called that folder "HNY," for Happy New Year.
If he couldn't get into a house the first time, he went back. Sometimes, he went back anyway; one residence in Tweed he visited on nine separate occasions, presumably because he could. A half-dozen times, homeowners returned before he was expecting them, or alarms sounded, and he had to flee out another door.
He entered through open doors (that trusting populace, back then, in Tweed) and windows, unlocked patio doors; he cut screens, removed screens and occasionally even a window, and pushed others in; at one cottage, he found the family's "hidden" extra key and just walked in; he once spent 30 minutes picking a lock to get in a house he wanted.
The one unwavering constant was his ferocious, unstoppable, insatiable drive.
In none of those pictures shown in court - not one - was Russ Williams ever smiling, or showing the slightest trace of pleasure: All this extraordinary effort just to watch himself watch himself, the same unreadable mild expression on his face.
Follow us on Twitter: