A month ago, the sex-assault case against Tyler Sanchez pivoted on a DA’s curious contention that low-cut jeans can be a breeding ground for random people’s DNA.

Now, because we’re talking Carol Chambers, the story naturally gets even stranger.

The 18th Judicial District Attorney keeps hounding Sanchez even though new evidence filed by the defense makes it increasingly questionable whether she’s prosecuting the right man for an attack that terrified Douglas County’s Stonegate neighborhood last summer.

Sanchez is 19, hearing impaired and has serious cognitive delays. He stands accused of breaking into an 8-year-old girl’s second-story bedroom and groping her in July.

I’ve written that the thin teenage redhead looks nothing like the 40ish, heavier, brown-haired intruder described by the victim.

I’ve also reported that DNA analysis of her panties — the key piece of physical evidence — excludes him. Chambers went out of her way to argue that the results don’t prove anything.

She offered this theory on why the girl’s underwear bore the genetic markers of her father and an unknown male instead:

“With the low-cut jeans that girls wear, she could have picked up anyone’s DNA off any surface her panties touched while they may have been riding up above her pants. I hate those low-cut pants,” she said.

No physical evidence or witness accounts tie Sanchez to the attack or to the rash of thefts, trespasses and break-ins in the neighborhood that prosecutors say led up to it. The only evidence against him is a short statement he gave as investigators wore him down over 38 hours with little food or sleep.

As Sanchez faces his preliminary hearing Tuesday, newly disclosed documents written by detectives in August 2009 suggest that DAs since have twisted his statements.

Deputies had serious doubts about what he was telling them, a sworn affidavit and other reports show.

In fact, they deemed comments he made during the interrogation to be so unreliable that they weren’t strong enough to charge him with the unsolved property crimes prosecutors have been saying he admitted to. DAs have misrepresented those statements in court as so-called “confessions.”

“Detectives have been unable to gather physical evidence or confessions sufficient enough to charge Sanchez with the crimes,” reads an investigation report.

He “was reluctant to provide information and when he did so it was vague. At times it seemed that Sanchez was unsure of what he did during the commission of each crime,” reads a police affidavit.

Making the case look even flimsier, authorities have destroyed the videotape of an early- morning interrogation of Sanchez after his arrest. The crucial footage, defense lawyer Iris Eytan says, was destroyed even after she repeatedly asked for it and a judge ruled to preserve it.

“No recording exists,” is how the DA’s office worded it.

How convenient.

Chambers is in no hurry to explain the latest kinks in her all-too-hinky case against a kid who, more than eight months after his arrest, still has everything to lose.

Why bother addressing the facts, after all, when she can blame the journalist reporting them?

“You are trying to undermine our credibility,” she’s accusing me. “There is no other reason to publish this story now instead of waiting to see what the truth actually is.”

Susan Greene writes Sundays, Tuesdays and Thursdays. Reach her at 303-954-1989 or greene@denverpost.com.