Coleman, an undercover narcotics officer, arrested 46 people - nearly all of them black - on charges of being cocaine dealers, and sent many of them to prison for a total of 750 years.
That was until Texas Gov. Rick Perry stepped in and pardoned them, and after a judge accused Coleman of being a liar who falsified evidence, a thief, and a racist.
Coleman defends his work in the interview, his first major one for American television, on the 36th season premiere of 60 Minutes. Correspondent Ed Bradley reports.
"There was a drug problem in Tulia, and there still is. They're selling drugs right now and I guarantee you they are," says Coleman. "Why did I do it for 18 months? Because I hate dope dealers and I hate dope. Period. That's it."
Early one morning in 1999, Tom Coleman's efforts culminated in the arrests of 13 percent of Tulia's adult black population. They were rousted out of bed, paraded in front of local television cameras in handcuffs - many of them half-dressed - and charged with selling cocaine to Coleman at various times over the course of his investigation.
The town newspaper declared: "Tulia's streets cleared of garbage."
"The defendants know when it boils down to it, when it right boils down to it, they handed me the dope, and I handed them the money," says Coleman.
One of those arrested was Freddie Brookins, Jr., 26, a former high school star athlete with no criminal record. He was sentenced to 20 years in prison.
"It wasn't an investigation," says Brookins. "It was just a roundup, a West Texas roundup, that's all it was."
Yul Bryant, a 33-year-old sales clerk, was charged with selling $160 worth of cocaine: "I was getting dressed, and when they knocked on the door, I was still in my boxers. They told me where I was going I didn't need no clothes."
Billy Wafer, a 45-year-old warehouse foreman, was charged with dealing 2.3 grams of cocaine to Coleman.
"I guess they wanted to be on the map," says Wafer. "They wanted to be on the map by arresting so many and making this the biggest drug bust that they ever had. Whether it was done right or wrong."
Why was nearly everyone that Coleman arrested black? Did he intentionally target the black community?
"I didn't intentionally target anyone in Tulia. It turned out that way. It's just where the road led me," says Coleman.
It may be no coincidence that the road led Coleman to the town's black community. It was well known that he had used racial slurs in front of his superior officers in Tulia.
"Everybody's making a big deal. 'Oh, God, he said the word 'nigger,' - like let's put him in the electric chair," says Coleman. "Well, yeah, that word 'nigger' was bad back in the '20s, '30s, '40s, and '50s and '60s and '70s, but now it's just a common slang, you know? I mean you can watch TV and hear that word, you know? It's a greeting."
Coleman, who doesn't consider himself a racist, told Bradley he used the "N" word to fit in with blacks during his investigation. He admits he also used it among his white friends: "The word nigger, yes sir, I've used that word. I've used it a lot. Yeah, 'What's up, nigger.'"
But when Bradley asks if that was a greeting he would use with him, Coleman replies, "Oh, no sir, not you."
The first defendants to face justice were quickly convicted in eight separate trials by nearly all white juries - only one of the jurors was black.
"I believe they already had a guilty verdict before any of us even went to court," says Brookins.
They were all given harsh sentences, ranging from 20 to 341 years in prison, even though the arrests had turned up no cocaine, no drug paraphernalia, no weapons, no money, or any other signs of drug dealing.
The convictions were based solely on the uncorroborated word of Coleman, who had followed none of the standard procedures routinely used in undercover drug operations across the country.
Coleman acknowledges that he wore no wire, had no partner to corroborate his testimony, collected no fingerprint evidence and had no surveillance video or still images to prove guilt. "[Such evidence] would have helped, but that's not how the operation went," Coleman tells Bradley.
If it went any other way, Coleman claims it would have been too dangerous and may have blown his cover. The only records he made of the supposed drug buys were notes of the names, dates and places - which he scrawled on his leg.
One of the harshest sentences of all - 90 years - went to Joe Moore, a 60-year-old hog farmer who has lived much of his life in this one-room shack. Authorities described him as the drug kingpin of Tulia.
"I didn't even know nothin' about a kingpin. I don't even know how a kingpin lives or nothing," says Moore. "I don't know nothin' 'bout that. But I know they live 30 times better than this. No, a 100 times better than this."
Coleman's great success at securing convictions came despite the fact that some of his cases fell apart, like the one against defendant Billy Wafer who had his case dismissed when he was able to show - with timecards - that he was at work at the local seed processing plant at the same time that Coleman testified Wafer was selling him cocaine.
"It never happened. He's that good," says Wafer. "He's that good of a liar that he convinced the D.A. and the Sheriff that that really happened."
Bryant had witnesses who said he was at a fair 50 miles away at the time Coleman said he sold him drugs. And that's not all.
"In my police report he said I was a tall black man with bushy type hair," says Bryant. "I'm 5 foot 7, I don't have, I haven't had any hair in like six, seven years. It wasn't me."
Case dismissed. And then there's the case of Tonya White. Coleman says she sold him $190 worth of cocaine in Tulia on Oct. 9, 1998, at 10:15 a.m.
"That's not possible because I was at the bank in Oklahoma City at 9:45 a.m. withdrawing $8. And they got my signature on my withdrawal slip," says White.
How does Coleman explain that? "All I know is, is that she was in Tulia selling me dope on that day," he says. "If I wanted to I could deposit a check in your bank account without you being there."
The deposit, with White's signature on it, was good enough to get her case dismissed. But her three siblings - Donnie, Kreemie, and Kizzie - were not so fortunate: They had already been sentenced to a total of 99 years in prison.
Elaine Jones, head of the NAACP Legal Defense Fund, spearheaded the effort to free the Tulia defendants. She says what happened there defies logic: "How do 46 drug dealers function in a community of 5,000 people? What's the client base? The market isn't there. Who are 46 drug dealers selling drugs to?"
But Coleman insists to this day that no matter what anyone says, those defendants in Tulia are guilty.
The jurors in the Tulia trials never heard what Coleman's superiors knew about his checkered background when they hired him.
Police officers he had formerly worked for said he needed constant supervision and had possible mental problems. They also said that he had abruptly walked off a previous job, leaving behind $7,000 in unpaid debts -- prompting the sheriff in that town to warn that, "Mr. Coleman should not be in law enforcement."
What's more, in the middle of Coleman's undercover investigation in Tulia, the man who hired him, the sheriff, arrested him on charges of stealing from a county where he had previously worked. He was permitted to continue his undercover operation in Tulia.
"It's a situation where all of the law enforcement officers in Texas who knew of Tom Coleman's checkered past said and did nothing at the time of these trials and pleas. Said nothing," says Jones.
How did it happen? How did it all go so wrong?
"It's an indictment of the war on drugs, it's the way the war on drugs is being fought," says Jones. "Washington is passing out money and nobody's supervising how it's being spent, applying the standards to these undercover operations."
The U.S. Justice Department has spent billions of dollars over the years funding drug task forces in small towns like Tulia. The more arrests and convictions a task force makes, the more money it receives the following year, which can be used in virtually any way it sees fit. In 1999, Coleman was rewarded for his efforts in Tulia.
The Attorney General of Texas named him outstanding officer of the year, but just six months ago, Coleman was called upon to defend his conduct before a state judge who was hearing appeals from some of those convicted in the Tulia sting.
The judge said Coleman's testimony was "absolutely riddled with perjury," and that he was "the most devious, non-responsive law enforcement witness this court has witnessed in 25 years on the bench in Texas."
"Yes sir. But that's his opinion. A lot of the juries during the trials, they spoke their verdict," says Coleman. "And that was a lot of juries. And that's just one judge."
But that one judge set the Tulia defendants free this summer. Among them were Joe Moore, Kizzie White, and Freddie Brookins, Jr.
"I know we can't have those three and a half years back, but we're gonna start where we left off," says Brookins.
As for Tom Coleman, he was recently indicted for perjury. He is also under investigation by the FBI for possible civil rights violations.
"It's took my career away from me, but I'm surviving. I'm taking care of my family. I'm paying my bills. And I'm not doing dope. I'm not selling dope to do it with either," says Coleman. "It's been hard, yes sir, it's been hard. But I'm proud of what I did in Tulia."
Tom Coleman's perjury trial is set to begin this fall. And to avoid what happened in Tulia, Texas is considering a bill requiring that all undercover drug stings have corroborating evidence before a defendant can be prosecuted.