It started with a drug raid in Houston and a shootout that left two people dead, five police officers wounded and one of them charged with murder, accused of making up information to obtain a warrant.
Now 69 people whose prosecutions relied on evidence from that accused officer are likely to have their convictions reversed under a process that began on Wednesday, and many more could in the future. The news had echoes of other high-profile police scandals, including the 1990s Rampart case in Los Angeles and the wrongful prosecution of dozens of African-Americans in Tulia, Texas, two decades ago.
Almost all of the 69 defendants have already served their sentences, which ranged from a few months in jail to four years in state prison. They had all pleaded guilty as a result of deals in which prosecutors relied on evidence from Gerald Goines, the narcotics officer who was charged last year with two counts of felony murder for his role in the botched raid.
The chief prosecutor in Houston, Kim Ogg, launched a review of all of the cases that Mr. Goines had handled. She said on Wednesday that her office had identified 69 defendants going back to 2008 who were prosecuted primarily based on his word. She said those defendants should now be entitled to the presumption that Mr. Goines had lied to obtain the convictions.
“We need to clear people convicted solely on the word of a police officer whom we can no longer trust,” Ms. Ogg, the Harris County district attorney, said in a statement.
Her office is filing papers in state court asking for judges to appoint lawyers for all 69 defendants so they can begin the process of seeking to have their convictions vacated. Their defense lawyers would have to show that the evidence supplied by Mr. Goines was material to their convictions.
Prosecutors are likely to oppose few, if any, motions from the 69 defendants to throw out their convictions, said Dane Schiller, a spokesman for Ms. Ogg. He said she might soon take the same step with many other defendants who were also investigated by Mr. Goines, once prosecutors complete a review of those cases.
There are believed to be about 180 other convictions since 2008 where Mr. Goines was a witness, but not the only witness.
Mr. Goines has pleaded not guilty to the murder and tampering charges. His lawyer, Nicole DeBorde, called Ms. Ogg’s announcement on Wednesday an effort to shore up her political support ahead of what is expected to be a tough re-election contest in next week’s Democratic primary.
“This is an election tool,” Ms. DeBorde said in an interview. “It’s just rotten for her to try to win this election at all costs on the back of this man’s due process rights.”
Houston prosecutors have already said they believe that two brothers convicted on Mr. Goines’s word are innocent. The brothers, Steven and Otis Mallet, were both arrested in 2008 by Mr. Goines, who claimed he had bought drugs from them. Both have already served time for those prosecutions.
According to a national registry maintained by three universities, there have been more than 2,500 exonerations in the United States since 1989. More than half of those cases involved allegations of official misconduct. And about a fifth of those exonerations were in cases in which the defendant had pleaded guilty.
Experts say some defendants — especially those represented by overworked public defenders — plead guilty to crimes they did not commit after being locked up in jail for days or months awaiting a resolution of their case, because the plea allows them to leave, credited with time already served.
In the Tulia case, nearly 50 people, almost all of them African-American, were exonerated and pardoned after they were convicted of fabricated drug charges based on the work of an undercover agent accused of racism and perjury. And more than 100 convictions were overturned in the aftermath of the Rampart Division scandal in Los Angeles, which involved physical abuse, evidence planting and false arrests.