Bryan Keith Francis, accused of killing 16-year-old Allison Castex in one of the most notorious crimes in St. Martin Parish, was ready to make a deal.

He would plead guilty and accept a life sentence rather than chance the death penalty on a first-degree murder charge.

But prosecutor Chester Cedars had no interest in negotiating if Francis didn’t ID his accomplice — the man who held Castex’s boyfriend at gunpoint while Francis sexually assaulted and killed the young girl just a few days after Christmas in 1997.

Tyrone “Dee” Davis had a child with Francis’ sister, and Cedars said Francis was reluctant to put the family breadwinner in jail.

Cedars had an idea.

On a hunch, he picked up the phone and called the state office that oversees child support to check on whether Davis was paying.

“There had been several complaints,” Cedars said in recent interview. “In a matter of minutes, Mr. Francis was giving us the identity of the second assailant.”

Cedars, who retired from 16th Judicial District Attorney’s Office on Friday, could tell stories for days about his 17 years as the lead prosecutor in St. Martin Parish.

In many respects, Cedars has been the face of justice in the rural parish, prosecuting every murder there for nearly two decades and most other major felonies. He even secured a guilty plea from country music legend Willie Nelson.

In addition, he’s represented a long list of public bodies over the years: St. Martin Parish Government, the School Board, the city of Breaux Bridge, the Sheriff’s Office.

When asked about the case he remembers most, he recalled one of his most difficult.

Marcus Donte Steele was accused in attacks on six women, many of them prostitutes or drug users he had picked up in Lafayette and taken to isolated areas in St. Martin Parish, where he brutally beat and sexually assaulted them.

“It was difficult to develop the case because of the lifestyles of the victims,” Cedars said.

DNA evidence had limited use, considering that some of the victims had willingly had sex with strangers, and Cedars said he was unsure if he could even locate all the victims when it came time of trial.

Steele had been formally charged in one of the attacks, and Cedars hoped to shore up that case by incorporating the allegations of five other victims. He was able to get them all at one pre-trial hearing.

“When they walked into the courtroom, they were holding arms together and it was a powerful signal we would do justice,” he said.

Steele soon pleaded guilty to forcible rape. He was sentenced in 2010 to 30 years in prison.

“I have taken every case and tried to approach it in the same manner, trying to realize a result that will bring as much justice as possible given the circumstances,” Cedars said.

Cedars also played a role in one the more high-profile court cases in recent state history, overseeing the investigation of serial killer Derrick Todd Lee’s attack of Breaux Bridge woman Diane Alexander.

She survived and went on to give powerful court testimony in the murder cases against Lee, who died of heart disease earlier this year while on death row at Louisiana State Penitentiary at Angola.

It hasn’t been all violent crimes for Cedars.

He oversaw a voter fraud investigation that netted guilty pleas from seven people in the contentious 2002 St. Martinville city elections. The elections were the first there since 1990, because city officials and the Justice Department had wrangled for 12 years over the racial balance of council districts. In the meantime, the 1995 St. Martin Parish elections had been marred by allegations of vote buying and vote selling, resulting in the indictment of 64 people in an investigation of election irregularities.

“We’ve come a long way,” Cedars said of the relatively scandal-free politics of recent years.

Of all the cases under Cedars’ belt, the one that likely attracted the most attention — literally worldwide interest — was a misdemeanor drug possession charge.

The defendant was Willie Nelson, arrested in St. Martin Parish in 2006 after State Troopers pulled over his tour bus on Interstate 10 in and found more than a pound of marijuana.

Cedars said troopers stopped the bus for a routine commercial vehicle inspection.

“Let’s just say it reeked of marijuana,” he said.

Nelson pleaded guilty, paid $1,024 and was sentenced to six months probation. The singer showed up to court in St. Martin Parish and sat in a packed courtroom with scores of other defendants. He later signed autographs for a crowd waiting outside the courthouse.

“That’s the one I take the most ribbing about,” Cedars said.

At 63, Cedars has no plans to stop practicing law.

He starts a new job July 11 as a deputy director in the state Attorney General’s Office civil division, a job he expects to be challenging but without the long days and weekends he routinely worked while balancing the demands of a being a full-time felony prosecutor while also representing local government.

“I have no other skills other than being a lawyer, and I knew I couldn’t go home and do nothing,” he said.

Follow Richard Burgess on Twitter, @rbb100.​