Russell Williams walked into an Ottawa police station with a smile, wearing the same boots he wore the night he entered Jessica Lloyd’s home.

Det. Sgt. Jim Smyth, a man with the most ordinary of names and demeanor, was waiting.

What happened over the next 10 hours is both fascinating and horrifying.

Smyth, a skilled but unimposing criminal investigator, methodically dismantled the façade of a monster. Caught on videotape, Williams’ confession offers a rare glimpsed into interrogation techniques.

“Internationally, people will be looking at this,” says Dave Perry, a retired homicide and sex crimes investigator who knows Smyth.

Perry, who now teaches interview techniques , calls Smyth’s interrogation “textbook.”

In 2003, Perry and Smyth coaxed a confession from Michael Briere, who murdered 12-year-old Holly Jones. Last year, it was Smyth who found the body of 8-year-old Tori Stafford .

OPP policy prevents Smyth from speaking to media for a month after the trial. But his performance speaks for itself.

Smyth is sincere and cordial. At the start, it seems as though he is buddies with Williams. Finding common ground with the suspect is key.

“You don’t have to speak to me,” Smyth tells Williams. He adds: “The reason for that is because the law considers me to be what we refer to as a person in authority. . . Probably similar to what you may be considered on your base.”

Later, Smyth mirrors Williams’ body language, putting his hand on his chin like the former colonel. He leans in when Williams does.

“He has to think that Smyth is his only friend in the world,” says Perry.

Next, Smyth reveals the evidence implicating Williams, one layer at a time.

Lying is fundamental to human nature when confronted with wrongdoing, says Dr. Louis B. Schlesinger, who wrote a book on sexual murder.

To get past that, interviewers present subjects with enough evidence to conclude lying is no longer an option.

Smyth lays down his first card: “Essentially there’s a connection between you and all four of those cases.”

Then he softly prods Williams . Where were you Friday? How did you find out about the death of Marie-France Comeau?

The former colonel’s answers are cues that he’s lying, Perry says. In police talk, it’s called “hedging.” .

“He’s very evasive,” Perry explains. “This is a man used to military precision and to not remember the day that a female member of the armed forces gets raped and murdered? It’s not the behaviour of a truthful person.”

As the hours pass, Smyth puts on pressure.

He asks for DNA. He reveals the former colonel’s tire prints match those near Lloyd’s home. He pulls out a photocopy of “identical” boot prints.

Smyth also uses silence to his advantage. Then, he speaks. “Your opportunity to take some control here and have some explanation that anybody’s going to believe is quickly expiring,” Smyth tells Williams.

“It’s hard to believe this is happening,” Williams says.

His smile is gone.

Finally, after Smyth asks where Lloyd’s body is, Williams looks up.

“You got a map?”

ANATOMY OF A CONFESSION

BUILD RAPPORT

“Are you a coffee guy?” Smyth asks. He slides Williams a cup.

“You have to ask yourself, who's a likeable, trusting person,” says John Kaster, retired Mountie and polygraph expert. “People who are well liked make the best interrogators.”

Smyth notes he and Williams are both in positions of authority.

“He's trying to show that he has respect for him. Whether he does or not,” says Dave Perry, a former investigator with the Toronto Police homicide squad and sex crimes unit. “As Freud would say, it's better to talk about what we have in common.”

PLAY THE FIRST CARD

Smyth asks Williams simple questions. The former colonel stalls, gives short answers, has a poor memory — all classic signs of deception. Police call it “hedging.”

It is important to remember that when a person is confronted with wrongdoing, lying is a fundamental part of human nature, says Dr. Louis Schlesinger, author of a book on sexual murder. “As an interrogator, you have to get beyond that.”

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“It’s so fundamental, it’s even in Genesis,” he adds. “When God confronted Cain about the murder of his brother, Abel he denied it.”

CHALLENGE THE MEMORY

“Do you remember what time you left the base that night?” Smyth asks.

Williams grimaces. He can't remember. Then he fumbles through a series of simple questions.

“He's used to military precision,” Perry notes. This is a telltale sign.

Soon, Williams crosses his arms and looks away from Smyth.

“When you add it all up he's being very evasive,” Perry says.

LAYER ON THE EVIDENCE

“What kind of tires do you have on your Pathfinder?”

Williams purses his lips. Scratches his back. Looks away. Furrows his brow. These all are non-verbal signs of stress, says Perry. And Smyth knows it. .

As the minutes go by, Smyth slowly reveals layers of evidence. Perry says it's important that he doesn't shut down. “You want to work him to a point of being defeated.”

SMYTH REVEALS THE BOOT PRINT

“You take a look at this print,” Smyth says. “These are identical.”

Then Smyth tells Williams police have a search warrant for his house.

“Right now because there’s a warrant being executed at your residence in Ottawa … so your wife now knows what’s going on.”

This is what experts call the “evidence bomb.”

“Look at his defeated passive position,” Perry points out.

One of the reasons Williams starts to break at this point is because he is smart. “He's somebody intelligent enough to know that the game is up,” Kaster says. “Most times, the slow-minded are harder to get a confession from than the relatively bright ones.”

THE CONFESSION

“I don't know what else to do to make you understand what's happening here,” says Smyth. He's just told Williams the investigation will cost up to $10 million. They'll spare no expense searching his computers and home.

“I want to minimize the impact on my wife,” Williams says.

Kaster says the former colonel’s wife appears to be his weakness. “As weird as it sounds,” he says. “It appears as if he really loves his wife or respects her or something.”

“That guy who couldn’t remember the details before now becomes full of details,” says Perry. “Now things that only the killer knows are going to start coming from the killer’s mouth.”