THE ROBBERY OF the armored car and the double homicide were never solved. I gave the FBI and the Dade County authorities as much information as I could about Dallas Klein’s relationship to the bookie Whitey Bruxal and the three collectors who were trying to dun Dallas for his sixteen-thousand-dollar tab. But I was firing in the well. The three collectors all had alibis, were lawyered-up and deaf, dumb, and don’t know from the jump. Whitey Bruxal returned from New Jersey of his own volition and allowed himself to be interviewed three times without benefit of counsel. I came to believe that the account I had given the authorities of Dallas’s connection to the gamblers was being looked upon with the same degree of credibility cops usually give the words of all drunks and junkies: You can always tell when they’re lying-their lips are moving.

I hung up my brief tenure with law enforcement in the tropics, attended my first A.A. meeting, a sunrise group that met in a grove of coconut palms on Fort Lauderdale Beach, and caught a flight the same day back to New Orleans.

That was over two decades ago. I believed Dallas made a deal with the devil and lost. I tried to stop the robbery and failed, but at least I tried, and I did not hold myself responsible for his death. At least, that was what I told myself. Later, I was fired from NOPD. Perhaps my dismissal was my fault, perhaps not. Frankly, I didn’t care. I went back sober to my birthplace, New Iberia, Louisiana, a small city on Bayou Teche, down by the Gulf of Mexico, and started my life over. It’s always the first inning, I said. And this time I was right about something.

TODAY I’M A DETECTIVE with the Iberia Parish Sheriff’s Department. I make a modest salary and live on Bayou Teche with my wife, Molly, who is a former nun, in a shotgun house shaded by oak trees that are at least two hundred years old. With a few exceptions, the cases I work are not spectacular ones. But in the spring of last year, on a lazy afternoon, just about the time the azaleas burst into bloom, I caught an unusual case that at first seemed inconsequential, the kind that gets buried in a file drawer or hopefully absorbed by a federal agency. Later, I would remember the pro forma beginnings of the investigation like the tremolo you might experience through the structure of an airplane just before oil from an engine streaks across your window.

A call came in from the operator of a truck stop on the parish line. A woman who was waiting on a tire repair had gone into the casino and removed a one-hundred-dollar bill from her purse, then had changed her mind and taken out a fifty and given it to the clerk.

“Sorry, I didn’t realize I had a smaller denomination,” she said.

“The hundred is no problem,” the clerk said, waiting.

“No, that’s okay,” she replied.

He noticed she had two one-hundred bills tucked in her wallet, both of them stained along the edges with a red dye.

I parked the cruiser in front of the truck stop and entered through the side door, into the casino section, and saw a blond woman seated at a stool in front of a video poker machine, feeding a five-dollar bill into the slot. She was dressed in jeans and a yellow cowboy shirt. She sipped at her coffee, her face reflective as she studied the row of electronic playing cards on the screen.

“I’m Detective Dave Robicheaux, with the Iberia Sheriff’s Department,” I said.

“Hi,” she said, turning her eyes on me. They were blue and full of light, without any sense of apprehension that I could see.

“You have some currency in your wallet that perhaps we need to take a look at,” I said.

“Pardon me?”

“You were going to give the clerk a hundred-dollar bill. Could I see it?”

She smiled. “Sure,” she said, and took her wallet from her purse. “Actually I have two of them. Are you looking for counterfeit money or something?”

“We let the Feds worry about stuff like that,” I said, taking the bills from her hand. “Where’d you get these?”

“At a casino in Biloxi,” she replied.

“You mind if I write down the serial numbers?” I said. “While we’re at this, can you give me some identification?”

She handed me a Florida driver’s license. “I’m living in Lafayette now. I’m not in trouble, am I?” she said. Her face was tilted up into mine, her eyes radiantly blue, sincere, not blinking.

“Can you show me something with your Lafayette address on it? I’d also like a phone number in case we have to reach you.”

“I don’t know what’s going on,” she said.

“Sometimes a low-yield explosive device containing marker dye is placed among bundles of currency that are stolen from banks or armored cars. When the device goes off, the currency is stained so the robbers can’t use it.”

“So maybe my hundreds are stolen?” she said, handing me a receipt for a twenty-three-hundred deposit on an apartment in Lafayette.

“Probably not. Dye ends up on money all the time. Your name is Trish Klein?”

“Yes, I just moved here from Miami.”

“Ever hear of a guy named Dallas Klein?”

Her eyes held on mine, her thoughts, whatever they were, impossible to read. “Why do you ask?” she said.

“I knew a guy by that name who flew a chopper in Vietnam. He was from Miami.”

“That was my father,” she said.

I finished copying her address and phone number off her deposit receipt and handed it back to her. “It’s nice to meet you, Ms. Klein. Your dad was a stand-up guy,” I said.

“You knew him in Vietnam?”

“I knew him,” I said. I glanced past her shoulder at the video screen. “You’ve got four kings. Welcome to Louisiana.”

ON THE WAY BACK to the office, I asked myself why I hadn’t told her I had been friends with her father in Miami. But maybe the memory was just too unpleasant to revisit, I thought. Maybe she had never learned that her father had been enticed into aiding and abetting the robbery of the armored car, if indeed that’s what happened. Why let the past injure the innocent? I told myself.

No, that was not it. She had paused before she acknowledged her father. As any investigative law officer will tell you, when witnesses or suspects or even ordinary citizens hesitate before answering a question, it’s because they are deciding whether they should either conceal information or outright lie about it.

It was almost 5 p.m. when I got back to the department. Wally, our dispatcher, told me there had been a homicide by gunshot wound on the bayou, amid a cluster of houses upstream from the sugar mill. I gave the serial numbers on the bills to a detective in our robbery unit and asked him to run them through our Internet connection to the U.S. Treasury Department. Then I tried to forget the image of Dallas Klein kneeling on a sidewalk, his fingers laced behind his head.

The sheriff of Iberia Parish was Helen Soileau. She had begun her career in law enforcement as a meter maid with NOPD, then had patrolled the Desire district and Gird Town and worked Narcotics in the French Quarter. She wore jeans or slacks, carried herself like a male athlete, and possessed a strange kind of androgynous beauty. Her face could be sensuous and warm, almost seductive, but it could change while you were talking to her, as though not only two genders but two different people lived inside her. People who saw her in one photograph often did not recognize her in another.

I not only admired Helen, I loved her. She was honest and loyal and never afraid. Anyone who showed disrespect regarding her sexuality did so only once.

A couple of years back, a New Iberia lowlife by the name of Jimmy Dean Styles, who ran a dump called the Boom Boom Room and who would eventually rape and murder a sixteen-year-old girl with a shotgun, was drinking from a bottle of chocolate milk behind his bar while he casually told Helen that even though he had overheard her male fellow officers ridiculing her at the McDonald’s on East Main, he personally considered her “a dyke who’s straight-up and don’t take shit from nobody.”