On Feb. 1, Mark Bretz died on an operating table in a Denver hospital. He'd had a heart attack six days after experiencing complications during surgery on his left eye.

Normally, such a death, while tragic, wouldn't garner much controversy or discussion. But Bretz didn't need surgery because of a hereditary medical condition or an accident.

A week before, early in the morning on Jan. 26, he'd been punched in the face at an Evansville bar. Bretz's family believes Ivall Sparks, the man who threw the punch, should be prosecuted in connection with his death - even if the punch itself didn't cause life-threatening damage.

At the time of Bretz's death, Sparks had already pleaded guilty to assault and begun serving a 90-day jail sentence. Prosecutors are now considering whether other criminal charges would be appropriate in the case, said Natrona County District Attorney Michael Blonigen.

Blonigen declined to comment on what those charges could be.

"We are still going through a ton of medical stuff," he said, along with consulting a pathologist in Colorado, where Bretz died.

"The case itself is pretty straightforward: How it happened and why it happened," he added. "But there is very tricky medical stuff."

Bretz's younger brother, Michael Fletcher, said the family is surprised Sparks isn't already facing a homicide charge

"No one in our family is saying this guy should serve the rest of his life in prison … but it would break our hearts if this guy did this again," he said.

Punch not disputed

There's no dispute Sparks punched Bretz. Sparks, 42, admitted as much to an Evansville police officer shortly after the incident, according to an affidavit filed by the officer.

The two were both at Butch's bar in Evansville in the early morning of Jan. 26. Bretz, a 50-year-old widower and Wyoming native, would come to the bar about once a month, according to Joy Kwedor, who's tended bar at Butch's for eight years.

According to Kwedor, Sparks' sister asked for a cab at some point. The cab driver later told her that when he arrived, Sparks and Bretz were apparently speaking to one another in low voices.

"It was low-key," Kwedor said. "I didn't even know there was a conflict and I mean, that's my job to spot that."

Kwedor didn't see Bretz get struck, but afterward he told her he'd been "blindsided." His left eye had a milky look to it and he couldn't find his glasses, which were later found under a cash register, Kwedor said.

Bretz told police he had been dancing with a woman whom he later found out was Sparks' sister, and when he was leaving, Sparks punched him from behind in the face, according to the affidavit. Sparks admitted to an officer that he had punched a man at Butch's. The man, he said, had repeatedly hit on his sister and had made an obscene reference toward her.

The officer arrested Sparks early that morning and booked him on an assault charge at Natrona County Detention Center.

Bretz ended up at Wyoming Medical Center, where he was examined by a doctor, who noted damage to the cornea, retina and lens of his left eye.

Later that morning, Bretz was flown to Denver for surgery on his eye. He had pre-existing medical problems - he smoked, had high blood pressure and poor circulation - and during the procedure, doctors had problems with his lungs, Fletcher said.

He never regained consciousness.

Guilty plea

Ivall Sparks, meanwhile, had his day in court. On Monday, Jan. 28, he appeared before Natrona County Circuit Judge Steven Brown on a misdemeanor assault charge.

At that court appearance, Sparks pleaded guilty and Brown sentenced him to 90 days in jail, court records show. The judge also ordered Sparks to pay restitution for the medical bills directly resulting from the assault.

Sparks was jailed at Natrona County Detention Center the same day, records show.

Four days after Sparks pleaded guilty, Mark Bretz died at the hospital. Family members expected Sparks would be charged in connection with Bretz's death, and they even discussed what would be an appropriate punishment for him.

Fletcher said he was shocked to learn Sparks wasn't immediately prosecuted for Bretz's death.

"I remember thinking this was unbelievable," he said. "It's pretty stunning. I've talked to Mark's friends and no one can believe this."

Blonigen said his office is still reviewing the case. Prosecutors have been compiling medical information, in addition to speaking to the Colorado pathologist.

"We have a lot of information we still have to obtain," Blonigen said.

Natrona County Chief Deputy Coroner Gary Hazen said the Adams County, Colo. Coroner's Office has jurisdiction in the case and hasn't finished yet it's report on Bretz's death.

The Lopez case

The Bretz case is unusual, but it's not without some precedent.

The Wyoming Supreme Court has considered a similar issue before, ironically enough, in another case that originated in Natrona County. In 2003, justices reversed the second-degree murder conviction of Kenneth Lopez, a Casper man who slapped the head of a friend during an argument. The friend died hours later.

In the Lopez case, the justices held that prosecutors did not prove Lopez killed his friend maliciously, which is a required element of second-degree murder. They sent the case back to Natrona County for a new trial, and a jury in 2004 convicted Lopez of manslaughter.

Prosecutors must consider two tests when considering a case like Bretz's, said University of Wyoming associate law professor Eric Johnson.

First, is the "but for" test of causation. It's a purely factual, scientific test: Would the death not have occurred but for the criminal conduct?

The second concern, the proximate cause, is less straightforward. A prosecutor must ask whether it makes sense to hold someone responsible for the death, Johnson explained.

"What it usually comes down to is evaluating whether there is some intervening event that plays so great a role that it supersedes what the defendant did," he said.

Blonigen says it will be a couple of weeks before a final decision is made on any additional charges. In the meantime, Sparks remains in custody at Natrona County Detention Center.

He is due to be released on April 27.

Reach Joshua Wolfson at (307) 266-0582 or at josh.wolfson@trib.com.