DURHAM, N.C. — Which of these pokers doesn't belong?

That's the question jurors in novelist Michael Peterson's murder trial could start mulling as early as this week, after both sides wrapped up rebuttal cases on Monday. Closing arguments could begin as early as Thursday.

Before Monday, the question of what happened to the "blow poke" fireplace tool that disappeared from the Peterson household was already a riddle. 

Prosecutors had used a stand-in version of the combination tool (used for prodding logs and blowing onto embers) in its place, saying Peterson used the missing weapon, or something similar to bludgeon his wife, Kathleen Peterson, on Dec. 9, 2001. And last week, defense attorney David Rudolph produced what he called the missing blow poke, saying that it had been found in Peterson's basement garage—Exactly when, and by whom, he didn't say.

That made two pokers.

On Monday, the blow poke conundrum got at least twice as complicated.

Candace Zamperini, the victim's sister who gave fireplace tools identical to one she owned (the demonstration tool) to her siblings as gifts in 1986, steered prosecutors to two more blow pokes, bringing the total to four.

In a blow to the prosecution, the gifted blow pokes matched the "missing" blow poke, lending provenance to the tool dramatically produced by the defense.

"Can we agree the missing blow poke has been found?" Rudolf asked lead investigator Art Holland, drawing an immediate, and successful, objection from prosecutor Freda Black.

Rudolf, who had examined the set over lunch with prosecutors, had reason to be confident.  After he entered the new blow pokes into evidence over the objection of prosecutors, jurors took turns examining the brass pokers one by one.

Most jurors gave the tools cursory inspections, matching them up for height, examining the fluted lip where the user would blow on the embers of a dying fire before stirring it with the tip.  One juror shook one of the blow pokes while peering at the solid metal tip,  as if to test how securely the tip was attached.

The blow poke conundrum is only one of the plot twists that have spun out of the 54-day, 64-witness testimony phase of Peterson's first-degree murder trial.  

In yet another dramatic development Monday, Det. Holland admitted that investigators had DNA tested a letter from Margaret Ratliff, Elizabeth Ratliff's daughter who Peterson adopted after Ratliff died in a similar stairway fall, to see if Peterson was her biological father.  The test, which came up negative, could have boosted the prosecution's theory that the defendant had a role in that death as well.

Blow poke drama aside, jurors could ultimately decide that physical evidence — such as the seven lacerations the state counts on the back of Kathleen Peterson's head, or the sheer volume of blood in the stairwell, or the blood spatter inside Michael Peterson's khaki shorts — is enough to convict him.

Peterson, 59, says he was by the pool when his wife fell to her death.

Following Friday's bombshell ruling that the state's injury mechanisms analysis expert had committed perjury, prosecutors sought on the final day of their rebuttal case to bolster that physical evidence by calling John Butts, the chief medical examiner of North Carolina.

Butts supervises Dr. Deborah Radisch the forensic pathologist who performed the autopsy on Kathleen Peterson, and his testimony largely dovetailed with hers.

Both Butts and Radisch cited the location, number and severity of the seven lacerations on the back of Kathleen Peterson's head in singling out blunt force trauma to the head as the cause of death. Defense experts count as few as four lacerations, citing some single impacts as looking like more than one.

While Butts stopped short of ruling out a stairway fall, he said the seven lacerations made it highly unlikely. To prove his point, he used a ballpoint pen to point out each laceration on an 8-by-11 photograph of the back of Kathleen Peterson's shaved head, counting from one to seven out loud for each group of jurors.

"You don't just get lots and lots of lacerations across the back top of the head," said Butts.

The chief medical examiner analyzes a slide of lung tissue.

Butts also contradicted the defense's position that the blood in the stairwell could have been coughed up by the dying victim.  Forensic scientist Henry Lee testified for the defense that Kathleen Peterson could have aspirated blood from her lungs onto the walls and stairs after she fell, but Butts said that was highly unlikely given the relative lack of blood in her lungs.

As a visual aid, Butts brought with him a slide of the only slice of Peterson's lung where blood was evident, pointing out two tiny dots corresponding to the "pin-head sized" specks.

Jurors passed the slide around, holding it up to the light in front of a magnifying glass Butts had supplied.

"In my opinion, there's no evidence of any significant aspiration of blood," said the medical examiner.  Bleeding in the lungs or nasal cavity, which commonly causes the sort of aspirated blood Lee demonstrated by spitting ketchup onto white poster board, would have been visible to the naked eye, in Butts opinion.

In all, Butts' testimony ably recapped the strongest aspect of the state's case: That the physical evidence reflects a homicide, not an accident.

But as he did with many witnesses, Rudolf took advantage of the leading questions he has the latitude to ask on cross-examination to introduce alternative theories of the case. Thus, he was able to advance the defense theory that the blend of alcohol, valium, muscle relaxant and antihistamines in Kathleen Peterson's blood could have made her dizzy enough to fall down the stairs.

In the defense's brief, one-witness surrebuttal case, Rudolf took the opportunity to ask Det. Art Holland why he had not tested the "missing" blow poke for Kathleen Peterson's DNA.  Rudolf and prosecutors had suggested that such testing could take as much as six months, while Rudolf noted that the DNA test on Ratliff's letter took only eight days.

Rudolph's unstated suggestion was that prosecutors may not have wanted to test the poker and support the defense's case in the process. 

On cross-examination by Freda Black, Holland adamantly maintained that the "missing" poker could not have been overlooked by his investigative team, which scoured the 10,000-square-foot household at least five times.

"That poker was not in that basement," he said firmly.

On Tuesday, jurors will have a chance to view the 500-plus pieces of evidence that have been entered during Peterson's trial, and Judge Orlando Hudson Jr. will preside over a charge conference at which prosecutors are expected to argue in favor of adding the lesser included charge of second-degree murder.

Court TV is broadcasting the trial live.