LUBBOCK, Texas — Across from a sprawling cotton field, among mobile homes in varying states of decay, one stood out: a double-wide with a new, expansive metal garage and the only paved driveway on the dead-end street.

It was here that an unemployed former computer repairman with a bad back ran what a drug informant called the biggest fentanyl ring in Lubbock. Federal officials said all Sidney Lanier needed was a computer and an elementary knowledge of chemistry to order shipments of the potent synthetic opioid from China and turn it into a highly profitable — and dangerous — street drug.

“It’s the Amazon of drug trafficking,’’ said Will Kimbell, the Drug Enforcement Administration’s resident agent in charge of the Lubbock office. “It’s almost as easy as that. This stuff is scary.’’

President-elect Donald Trump has promised that his border wall will stop the illegal drugs flooding into the United States from Mexico. But increasingly the most powerful opioids destroying lives and devastating communities from Maine to Texas are arriving through a different route: from China. Via the US Postal Service.

Independent operations like the one Lanier is alleged to have run are growing and spreading fentanyl to new areas, greatly complicating enforcement efforts. Last month, federal agents raided two Utah homes where they discovered a pill press, bulk powder believed to be fentanyl, and thousands of fentanyl pills. Investigators said the drug was shipped from China to multiple addresses in the state. Similar operations have been discovered this year in California and New York.

In Lubbock, STAT interviewed police and DEA agents and reviewed hundreds of pages of court records to construct a frightening case study of how quickly fentanyl can arrive on the scene, the destruction it causes, and the shockingly simple steps involved in becoming a fentanyl dealer.

Buying, mixing, and selling fentanyl takes none of the brains and ingenuity of the fictional Walter White, the chemistry whiz-turned-methamphetamine dealer in the television show “Breaking Bad.’’ Lanier and his crew were brazen, sloppy, and battling their own addictions, officials alleged. Yet they appear to have raked in tens of thousands of dollars during the two-plus years they operated, according to court records.

Two local women, including the niece of Lubbock’s former mayor, allegedly served as Lanier’s distributors. They cooked the fentanyl on a kitchen stove, mixing it with two simple ingredients found at auto supply shops and pharmacies.

Use of fentanyl has exploded in many states, driven largely by how easy it is to get and make. It is also far more potent than other opioids, such as heroin and pain pills, and far more profitable for dealers. In many places, it is now the leading cause of fatal overdoses. The victims often think the drugs they’re taking are less dangerous, but dealers mix fentanyl with heroin to give that drug extra potency. Mexican cartels, believed to still be responsible for most of the fentanyl trade in the United States, produce the drug in pill form, making it look like hydrocodone, Xanax, and other prescription drugs.

Lubbock police first started hearing about fentanyl on their streets in 2015, although as far as they knew, no one was dying from taking the drug. Then in April, a 55-year-old woman died. Less than a week later, a 32-year-old man was found dead. In June, there was another death. In September, a 20-year-old man was dead, and two days later, a 51-year-old man. In each case, the medical examiner determined the death was related to fentanyl.

Lanier and his alleged distributors were arrested in October, but there is evidence of other independently operating fentanyl dealers in Lubbock, including one who called police recently to report that another dealer stole 250 grams of fentanyl from him that he had ordered online from a company in Russia.

Fentanyl shipments are particularly difficult to detect because of the small quantities involved. “You send an e-mail, pay for it, and a couple weeks later you have 300 grams of fentanyl,’’ Kimbell said. “And you have a potential profit of a half-million dollars.’’

All it took for Lanier to allegedly get started was a simple Internet search.

Laboratories in China offer to sell various forms of fentanyl on the Web, no questions asked. And the 36-year-old Lanier allegedly told police he found instructions online for preparing fentanyl for sale.

Although he dropped out of school in the 10th grade when his girlfriend became pregnant, Lanier was adept at using computers. He obtained his GED, did a brief stint in the Army, and took classes at a local college. For a number of years, he ran a computer repair business in Lubbock.

He allegedly purchased the drug through the so-called DarkNet, which uses special browsers so people can anonymously visit sites that are not otherwise viewable.

The Chinese labs shipped samples, if requested, and guaranteed delivery. That meant if customs agents intercepted a package or it failed to arrive for any reason, the lab would send the same order again at no charge. In some cases, officials believe the Chinese labs have routed fentanyl packages destined for the United States through Canada to avoid seizure.

Fentanyl comes in many forms. Labs can tweak its chemical structure slightly to make analogs of the drug, which was developed as a prescription pain reliever nearly 60 years ago by Janssen Pharmaceutical. In Lubbock, investigators have identified at least five different forms of fentanyl on the street — including some that are not on the list of controlled substances banned in the United States. As the DEA discovers and bans new analogs, chemists in China are already at work on even newer synthetic products.

The fact is that the Chinese labs have solved the most challenging chemistry problem: producing the fentanyl, which is a complex procedure that is extremely difficult to replicate outside a commercial laboratory and without advanced training.

Lanier, who was known as Caleb on the streets of Lubbock, allegedly received the fentanyl in crystalized form. For one order from a Chinese lab, he allegedly paid $3,500 for 300 grams of pure fentanyl. He typically mixed the fentanyl with methanol — a chemical that is the primary ingredient in antifreeze — to suspend the drug in liquid.

He would sell a vial containing 8 grams of fentanyl for $15,000 to $20,000, often to two women who served as his main distributors, according to court records. Lanier’s profit on that one 300-gram order, if he sold all of his vials, would have been over a half-million dollars, officials said.

To get the fentanyl ready for sale, there was one more step required.

In the kitchen of their apartment in a drab complex of two-story brick buildings, the women who allegedly served as distributors took the vial prepared by Lanier and poured it into a pan on their stove, according to a police affidavit. They mixed in a sugar alcohol used in several medications available in pharmacies. They would heat the mixture for 45 to 60 minutes, drying it into a powder.

A good batch produced from one vial could fetch $45,000 to $60,000 on the street in Lubbock.

Lanier and the women, Jessica Holl and Jamie Robertson, have been charged in a federal criminal complaint with conspiracy to distribute fentanyl. Lawyers for Holl and Robertson declined to comment, and Lanier’s lawyer did not return phone calls.

Investigators have shifted their focus to determining whether the fentanyl allegedly sold by the crew is linked to any of the five fatal overdoses confirmed in the city last year. So far, no one has been charged in the deaths.

Lanier is remorseful, his mother, Marla, said in a telephone interview. Sidney Lanier had a happy childhood in Clovis, N.M., according to a 2004 psychological evaluation he underwent as part of a divorce proceeding.

His mother and others trace Lanier’s alleged use and sale of opioids to a back injury suffered about 15 years ago, when he was run over by a truck.

He endured excruciating pain and had to give up the computer repair business because he could no longer lift the equipment he was fixing, his mother said. He went on government disability.

“It changed his life forever,’’ his mother said of the injury.

Marla Lanier said her son underwent numerous surgeries and visited doctors throughout Texas seeking relief from his pain. His Facebook page shows an image from a procedure he underwent in 2010. Screws inserted into his spine are visible.

Lanier allegedly began to abuse opioids. He took the fentanyl he ordered from China, often using himself as a guinea pig to check the quality of a shipment and to get relief from his pain. His wife told police she witnessed her husband injecting himself with pain medication.

“He didn’t ask for this life,’’ his mother said.

In the end, fentanyl allegedly offered Lanier both relief from pain and a new source of income. It may also cost him his freedom.

David Armstrong can be reached at david.armstrong@ statnews.com. Follow him on Twitter @DavidArmstrongX.