John Ferak

USA TODAY NETWORK-Wisconsin

Millions of Netflix viewers who watched “Making a Murderer” know that the license plates of Teresa Halbach’s Toyota RAV4 are one of the most intriguing mysteries surrounding the circumstances of her homicide.

Related: “Making a Murderer” coverage, archived stories and more

Her sports utility vehicle was found on Saturday, Nov. 5, 2005, on the outer ridge of the Avery Salvage Yard – missing its license plates. But why would the plates be gone?

Why would the murderer crouch down, armed with a screwdriver and methodically unscrew both plates from the front and the back?

If the killer was Steven Avery, why would he carry those plates to another part of his family's 40-acre junkyard and flip them into the backseat of a wrecked vehicle?

The vital discovery of the license plates on Tuesday, Nov. 8 also coincided with another suspicious finding that day: Manitowoc County Sheriff's Lt. James Lenk and Sgt. Andrew Colborn revisited Avery's bedroom and noticed a spare key on the carpet near Avery's bed.

"I believe I said to myself, damn, how did I miss that?" Colborn later testified during Avery's murder trial.

Avery's bedroom had already undergone numerous extensive searches between Nov. 5-7, 2005. Nobody in law enforcement saw any spare key on the floor. The key, it turned out, contained the Avery's DNA, but oddly, not the victim's DNA.

The circumstances surrounding of the finding of Halbach's license plates that very same day, the USA TODAY NETWORK-Wisconsin found, are also curious.

Timeline: History of the Steven Avery case

The entire Avery Salvage Yard - roughly 4,000 vehicles - was searched during daylight on Sunday, Nov. 6. According to 2005 media reports, as many as 200 police officers combed the junked vehicles of the salvage yard that particular day.

Dozens of volunteer firefighters were also on hand, helping check underneath the hoods and inside the trunks of those vehicles for evidence including the victim's body. Even though hundreds of police officers and firefighters were already hovering over these vehicles all day long, the canvassers apparently weren't looking inside the vehicles for clues.

That Sunday, no significant clues were found despite the massive all-out search blanketing the 40-acre junkyard.

Three sheriff's officials arrived early the next morning that morning to go back into the junkyard and check for vehicles that were supposedly missed by the volunteer firefighters and police officers the day before.

One was Sgt. Bill Tyson of the Calumet County Sheriff's Office. Assigned to accompany him were Lenk and Colborn.

“Our responsibility was to find any remaining vehicles that did not have the trunk popped by the fire department and if we located those vehicles, our responsibility was to open the trunk areas of all those vehicles,” Tyson later testified.

That Monday morning, the three men were extremely busy.

“Yes, we found numerous vehicles that were not taken care of so we did use crowbars wherever necessary to get them trunk lids open," Tyson testified.

Colborn testified at Avery's trial that he thought he arrived between 6:30 and 7:30 a.m. on Nov. 7.

“And (Tyson) informed us that our assignment that day was to go into the Avery Salvage Yard and open any trunks of vehicles that had not yet been searched,” Colborn testified. “Apparently they couldn’t find the keys for these vehicles and we were to look inside the trunks of these vehicles.

"Lt. Lenk was with me that day," Colborn testified. "That (assignment) took the better part of the morning."

Tyson, Lenk and Colborn did not report finding any significant evidence that morning.

And just like the volunteer firefighters the day before them, they apparently were not asked to check inside any of the several thousand vehicles at the junkyard, trial testimony reflects.

That instruction from the command staff would come the next day – the day after Lenk and Colborn were among the first law enforcement officers to wander around the Avery junkyard.

Tuesday, Nov. 8, marked another massive all-out search of the junkyard by dozens of volunteer firefighters from around the region, along with the Wisconsin State Patrol.

These were the same public safety officials who were summoned to the junkyard two days earlier to check in the trunks and underneath the hoods, but apparently not inside the vehicles.

If searching the vehicles was a high priority, why not complete the process the very next day instead of 48 hours later?

As it turned out, the day after Lenk and Colborn roamed the junkyard, William Brandes Jr., a volunteer with the Brillion Fire Department, came upon two dynamic pieces of evidence that further solidified special prosecutor Ken Kratz's case against murder suspect Avery.

Brandes testified that after rummaging through about 50 vehicles, he came upon the pair of Halbach's license plates. They were inside the backseat of a junked station wagon within the Avery Salvage Yard.

He remembered being told to be on the lookout for certain clues, such as a shirt and jeans, that might belong to Halbach – and her license plates.

“I was just walking along," he testified. "I was actually on the driver’s side searching and there were a bunch of weeds. We crawled through the weeds and looked in. And I peered in the back and behind what would be the passenger side seat.

“The backseat was folded down flat and behind the passenger side seat was a set of what ended up being license plates.”

The plates, Brandes saw, had been folded "twice inward."

"So you could not see a number ... on them," Brandes testified. “I picked them up. And when I figured they were license plates, I had slowly peeled them open. I gently sent them back down inside the car.”

Cindy Paine, a Wisconsin State Patrol trooper, testified she was in the same area of the junkyard when Brandes made his discovery.

“He said it was the license plate we were looking for and he had pointed it out to me,” Paine testified. “I saw a license plate that had a bend in it and it was in back of a station wagon.”

Paine took photos of the license plates, which were eventually presented in court as trial exhibits to help secure Avery’s murder conviction in 2007.

Paine was part of a group searching the junkyard that day that included state troopers, sheriff’s deputies, firefighters and citizen volunteers.

At Avery's trial, his lawyers Dean Strang and Jerry Buting argued their client had been framed by the Manitowoc County Sheriff's Office in retaliation for bringing a $36 million federal civil rights lawsuit against the sheriff's office and former sheriff Tom Kocourek.

They argued that Lenk or Colborn planted Avery's blood inside Halbach's RAV4 and put her spare ignition key inside the murder suspect's bedroom on Nov. 8.

Both Lenk and Colborn denied planting any evidence during their trial testimony.

During cross-examination, Strang reminded Colborn that he had called into his police radio dispatch on Thursday, Nov. 3 reciting the letters and numerals for Halbach's license plate – and then Colborn asked for confirmation of her vehicle's make and year.

Colborn denied he was standing at the Halbach vehicle when he called into dispatch. Colborn testified he was familiar with the salvage yard from being a customer there over the years to buy spare parts for one of his personal vehicles.

Two days after Colborn inquired about Halbach's license plates, her SUV was found on the outer perimeter of the salvage yard - missing both of its license plates

Less than 48 hours afterward, Lenk and Colborn were directed to search portions of the junkyard for clues.

Then, that following day, the junkyard was ordered to be re-checked again by the slew of volunteer firefighters and Wisconsin state troopers.

Only at that time did the license plates for Halbach's vehicle surface.

Avery was arrested on Nov. 9.

John Ferak: 920-993-7115 or jferak@gannett.com; on Twitter @johnferak