The 12 jurors filed solemnly into the downtown Phoenix courtroom after lunch last November 14, a Monday.

It had been three long months since opening statements in the tragic murder case of Arizona vs. Jeffrey Martinson.

For their troubles — and there were many — the jurors were paid all of $12 a day, plus mileage and possible reimbursement for some of their lost income.

Martinson, a 45-year-old onetime business consultant, sat at the defense table with his attorneys, Mike Terribile and Treasure Van Dreumel. He was as pale as death — no surprise, in that he had been incarcerated in a Maricopa County jail for seven years.

Martinson had been arrested shortly after the August 2004 death of his 5-year-old son, Josh. The boy died at Martinson's apartment in Ahwatukee during a court-ordered weekend visitation.

Josh's mother, Kris Eberle, had alerted Phoenix police after Martinson didn't return their son on time and wasn't answering his phone.

Police found Josh's cold body on the upper bunk of a bed, moments after a neighbor entered through an unlocked arcadia door and found Martinson unconscious in his own bedroom, a plastic bag over his head and superficial cuts on his wrists from a box cutter.

A county pathologist ruled that the cause of the boy's death was "acute carisprodol toxicity."

The manner of death was listed as a homicide.

Pathologist Dr. John Hu concluded that Josh had ingested enough of the prescription muscle relaxant Soma to kill him. The amount of the drug in Josh's gastric contents was less than one 350-milligram pill, a normal adult daily dosage.

Prosecutors alleged that the ex-couple's vicious ongoing battles in Family Court — Martinson was losing — had pushed him to exact the "ultimate revenge" against Eberle, the death of their son.

But Deputy County Attorney Frankie Grimsman hadn't alleged the case as a premeditated first-degree murder, in which a killer plans his deed ahead of time, even briefly.

Instead, Martinson was charged under Arizona's "felony murder" rule. It holds that if a person dies while someone else is committing or attempting to commit crimes including arson, robbery, rape, or the most serious level of child abuse, it's legally the same as if the defendant plotted the killing.

To win a "felony murder/child abuse" conviction, the state needed only to prove beyond a reasonable doubt that Josh's death was an inadvertent consequence of his father's intended child abuse.

In this instance, this would mean that Martinson had given Josh the Soma pill with the intent to hurt but not kill him.

In October 2004, outgoing Maricopa County Attorney Rick Romley approved his Family Violence Unit's decision to seek the death penalty.

To secure a "felony murder" conviction, prosecutors were supposed to have the legal burden of proving that Martinson actually had drugged his son (the official cause of death), no matter the intent.

Could the child have taken the drug himself, or could his father have "recklessly" or "negligently" (less-serious components of the child-abuse laws) stupidly given it to Josh to calm him down.

How Josh got the Soma into his system is a lingering mystery; and one juror later said "only Josh and his father know the answer to that one."

But a little boy was dead, and he shouldn't have been.

This apparently sold prosecutor Frankie Grimsman on seeking Jeff Martinson's execution.

Grimsman argued at court hearings and in legal papers that any level of child abuse leading to Josh's death constituted felony murder.

Superior Court Judge Sally Duncan asked Grimsman shortly before the trial began last August what she would tell jurors about Jeff Martinson's alleged mind-set.

"Obviously, frustration and anger at Ms. Eberle was a factor in what the defendant was feeling that day and what probably contributed to the build-up of emotion," the prosecutor said, sounding as if she were describing a premeditated murder.

"We don't know what was going into his thinking at the time that this Soma was being administered," she continued, adding that Martinson definitely had given it to Josh to injure the boy.

Then came the clincher.

"In the state's opinion," Grimsman said, "we simply have to prove that a child abuse occurred, and in the course of this conduct [giving Josh the pill], this child died — and that's felony murder."

That was akin to what she had told the judge in September 2009. Comparing the case to an unspecified Greek tragedy, she had said then, "It is the very nature of the relationship of Kristen Eberle and [Martinson] that served as the motive for murder. The anger and resentment that built over time caused [him] to murder his own child."

Jeff Martinson never did admit to giving his son the drug. He testified dramatically that Josh accidentally drowned, something prosecutors could not refute with their medical witnesses.