The negotiations began in 1999, when Schneider's son Danny was killed at midnight on the streets of New Orleans Lower Ninth Ward, triggering the devastated pharmacist to ignore the advice and even incite the anger of the New Orleans Police Department by launching his own gum-shoe investigation that ultimately resulted in identifying and convicting his son's killer.

Then, as if beating those enormous odds and dealing with his family's searing heartache were not enough, Schneider channeled his pain into a second crusade every bit as heroic if not quixotic -- shutting down the state's largest opioid mill in New Orleans East, paying homage to the son who was stolen from him by the drug underworld.

"I went at warp speed to do my best," Schneider said, "but there were so many things along the way, both in solving Danny's murder and in the (opioid) case, where I said to God, 'OK, God, you did this for me and I'm going to do this for you, but why are you making it so hard? Why, after telling me to go do this, do police get in my way and goons chase me?'"

Schneider's 20-year mission to secure a resolution to his 22-year-old son's death and to protect young people like him has been transformed into a riveting Netflix documentary series titled simply, "The Pharmacist."

The documentary already has garnered global acclaim for its exposure of the prescription drug crisis that claimed a half-million lives in the U.S. between 2000 and 2015; 60 percent of those deaths were attributed to opioid overdoses.

Schneider's first child, Danny, was born in 1976. Schneider said he and his wife were Catholic by birth and heritage, but he admits they probably would have considered themselves "occasional" Catholics in those days.

"That was until my son's death – and I hate to say that," Schneider said. "For a very brief moment – maybe a week or less – I was angry at God, but I came around real quick. At first, it was not just love of God – it was desperation. Then it became love, and then it became an agreement. I actually started sensing that God was helping me."

There were many heroes along the way – the woman, Shane Madding, who endangered her own life by identifying and then agreeing to testify against the killer despite persistent death threats; the pastor, Terence Reed of Lighthouse Ministries in the Ninth Ward, who agreed to walk the streets, along with a cadre of African American men recovering from drug and alcohol addictions, introducing the white pharmacist from Chalmette, Louisiana, to residents while he posted flyers on telephone poles and knocked on doors.

"There's a bunch of what I call mini-miracles," Schneider said. "If you're not a believer, some people would explain them away as coincidence. All my friends were on my case. My wife was on my case. The police were fighting me almost (to stop). I was very close to quitting."

Just as he was prepared to give up his investigation, Schneider used an address-based telephone directory to call every house within a half-mile radius of Danny's shooting. Almost everyone said they knew nothing or hung up. He finally got Shane Madding to tell him what happened, and her testimony led to Jeffrey Hall pleading guilty to manslaughter.

Schneider thought it was the end of an exhausting family saga, but as he continued to work at Bradley's Pharmacy in Poydras, he noticed a disturbing flow of young people – about the age of his late son – bringing in prescriptions for OxyContin, Xanax and the muscle-relaxant Soma.

That three-drug package was known on the streets as the "Holy Trinity."

About 90 percent of the prescriptions were written by Dr. Jacqueline Cleggett, a doctor of internal medicine and pediatrics who had opened a "pain management" clinic in New Orleans East, just a few miles from the St. Bernard Parish line.

The young kids triggered an alarm in Schneider.

"This wasn't a middle-aged guy walking in who was working on an oyster boat who had hurt himself and had some legitimate pain," Schneider said. "My son had died at 22, and these were 20-year-olds walking in, looking perfectly healthy."

Because of what happened to his son, Schneider felt compelled not to look the other way. On a car trip to watch the New Orleans Saints play a road playoff game in January 2001, Schneider was wrestling with embarking on another major investigation when he looked through his windshield and saw a clearly defined cloud formation in the shape of a cross.

That convinced him to move forward. The Schneiders got back to the New Orleans area around midnight, and the pharmacist remembered that many people coming into his store to have their prescriptions filled told him Cleggett worked late hours – well past midnight – at her clinic.

"So, now it's about 2 o'clock in the morning and we pull up to the clinic and park across the street to videotape," Schneider said. "My wife sees this and she goes, 'Oh, my God. It's 2 o'clock in the morning, and there's a hundred people there!'

"There were actually cabs pulling up, parking and then the people would run inside and then come back into the cab and leave. When I went out there, I didn't think it was going to be as bad as my patients had been telling me. It was way worse."

Schneider's evidence against Cleggett eventually led to her pleading guilty to one of 37 counts of conspiring to dispense and distribute a controlled substance.

Now that his crusade to protect others has raised awareness of the dangers of opioids and other controlled substances being used and sold on the black market, Schneider hopes his efforts will save other lives.

His story has been a major impetus for an umbrella federal lawsuit, centered in Cleveland, in which dozens of states and municipalities are seeking compensation from various pharmaceutical companies for failing to properly warn consumers about the addictive properties of OxyContin and other prescription medications.

"The whole reason I did this, in addition to my commitment to God, is to save lives," Schneider said. "One life is worth it, but I'm not trying to save just one life. I want to save hundreds of lives, and I'll lay it on the line for as long as I can. God is all over this thing."

Finney is executive editor/general manager of the Clarion Herald, newspaper of the Archdiocese of New Orleans.