PHILADELPHIA — For more than two decades prosecutors in Philadelphia were convinced they knew exactly what happened to Louise Talley, who was murdered inside her home in 1991.

Now, they’re not so sure.

But they’re willing to stake the integrity of the American justice system on their belief that Anthony Wright had something to do with it.

Last week, Wright went on trial a second time on charges that he murdered the 77-year-old widow during a drug-fueled burglary. A jury found Wright guilty of murder in 1993 and he was subsequently sentenced to life in prison without the possibility of parole, narrowly escaping the death penalty. Wright spent the next 23 years in prison before DNA evidence proved that another man was responsible for the crime.

Yet Wright is back on trial for the same murder today.

A judge vacated Wright’s conviction in 2014, but now he’s being tried again for the same crime. (Since a jury did not acquit Wright of murder in the first place, the Constitution’s prohibition on “double jeopardy” can’t protect him.) Now the Philadelphia District Attorney’s office led by Seth Williams argues that Wright must have had an accomplice who left the incriminating DNA.

That man was Ronnie Byrd, a former crackhead who had racked up a long list of felonies including convictions for assault, robbery, and receiving stolen property before he died in prison in 2013.

Having tried and failed to put Wright away for life without scientific evidence, the DA is trying again.

A spokesperson for the district attorney’s office refused to comment on the case, citing agency policy. Wright’s attorneys did not return phone messages seeking their input. However, Bradley Bridge, a veteran attorney with the Defender Association of Philadelphia who represented Wright as a juvenile, spoke to The Daily Beast about the case and said the DA’s inconsistencies are troubling.

“They advanced one theory for decades, discovered that it’s undercut by the science, and now they’re advancing a different theory, which is totally at odds with the first and doesn’t make much sense anyway,” he said. “The prosecutor is stretching to come up with a theory of this case that isn’t supported by the evidence.”

In fact, the DA’s office was so hell-bent on keeping Wright in prison that it fought to prevent DNA testing from even taking place originally. It took attorneys from the Innocence Project at Benjamin N. Cardozo School of Law in New York nine years of legal wrangling (all the way up to the Pennsylvania Supreme Court) to get prosecutors to drop their objections.

For all the controversy surrounding Wright’s retrial, it’s undisputed that Talley met a horrifically violent end. According to court records, when police entered her home on Oct. 19, 1991, at the behest of concerned family members, they found the property had been ransacked. The victim’s body was discovered on the second floor, naked, and lying face down in her bed. An empty blood-soaked purse was found beneath her body. On the floor next to Talley police retrieved a bloody kitchen knife from inside the folds of her discarded bathrobe.

The medical examiner would later rule that Talley died as a result of blunt force trauma and multiple stab wounds to her neck, chest, and back. A semen stain on her sheets indicated she had been raped before she died, investigators said.

Wright was brought in next morning for questioning. If police are to be believed, he waived his Miranda rights and provided a full confession all within the time it takes to watch an episode-and-a-half of Law & Order. The nine-page statement he signed describes in detail how he forced Talley to strip, raped her, and then stabbed her when she began to struggle. As all this was going on, Talley was begging him not to hurt her, according to the statement.

Wright recanted the confession at trial, claiming he had been handcuffed to a chair by police and forced to sign it without reading it. Wright’s interrogation was not recorded, and the only witnesses were the detectives asking the questions—the ones Wright says promised to “skullfuck” him if he didn’t cooperate.

In 1993 a judge denied a motion by Wright’s court-appointed lawyer to suppress the confession, on the grounds that it was given “voluntarily.” Astoundingly, the judge overseeing Wright’s case, Sandy L.V. Byrd (no relation to Ronnie Byrd), ruled to allow the confession as evidence in his current case. The DNA evidence proves that significant portions of Wright’s questionable confession could not have happened as described.

While the original investigation said it discovered semen on Talley’s sheets, follow-up testing showed there was none present on items retrieved from the bed. Instead, ejaculate was found inside Talley’s vagina and rectum (where the medical examiner failed to discover it the first time). Most importantly, DNA from the semen matched with Byrd and excluded Wright.

What’s more, the prosecution’s smoking gun—clothing items long believed to have been worn by the killer—turned out upon further inspection to be less than incriminating.

Wright’s confession described the clothes he was wearing at the alleged time he killed Talley as a black Chicago Bulls sweatshirt, a pair of blue jeans, and Fila sneakers. Detectives testified that they recovered these items from Wright’s home the day of his arrest and that they were spattered with blood. Wright and his mother have long maintained the items weren’t his, and sophisticated testing failed to turn up any of his DNA inside the clothing. Instead investigators found forensic evidence suggesting that the clothes belonged to Talley, not her murderer.

Marissa Boyers Bluestine, legal director of the Pennsylvania Innocence Project at Temple University, said the district attorney’s office will need to articulate how it made such a profound error about such an important piece of evidence.

“On the one hand, it seems highly unlikely that the police walk into a crime scene, take clothing away and plant it on him,” she told The Daily Beast. “But there are a host of questions there. We’re talking about clothing that we now know was not Mr. Wright’s. To be honest I cannot come up with a sustainable narrative to explain it.”

The clothing evidence is so integral to the prosecution’s case against Wright that last Wednesday the DA’s office asked for a continuance so it could test a single strand of hair that was only recently discovered in the sweatshirt. Even if that hair turned out to be Wright’s, the absence of his DNA as a dominant source on the clothes is problematic given the prosecution’s original narrative.

“One would expect to find the suspect’s wearer DNA on contact points tested unless a barrier such as under clothing prevented a transfer of skin cells to the garment,” said Joe Minor, a former forensic supervisor at the Tennessee Bureau of Investigation who now consults on DNA evidence.

The absence of a single mention of Byrd in Wright’s confession suggests either the person who concocted the statement didn’t know the man existed, or Wright purposely left Byrd out when writing the nine-page statement and took the full blame in a murder case where the death penalty was likely.

For his part Wright insists he never knew Byrd and since the time of his trial has steadfastly proclaimed he is innocent. Yet there’s still the perplexing question of why a 20-year-old with presumably nothing to lose would sign what could have amounted to his own death warrant. Wright was facing capital murder charges; a deadlocked jury during the sentencing phase of his trial spared him from that fate.

Talley was murdered in the Tioga-Nicetown neighborhood, where drug gangs competed for influence with cadres of corrupt cops as the city notched more than 500 murders. The precinct’s narcotics unit was overseen by supervisors known on the street as the “Four Horsemen of the Apocalypse.” They were later convicted of shaking down so many drug dealers, planting so much evidence, and cracking so many skulls that hundreds of drug cases would later be reversed.

The attitude of most Philly cops in the 1980s and 1990s was summed up in a statement by Officer Christopher Rudy, who was on duty when he helped a friend violently settle a personal dispute in 1993.

“I’m a cop. Ain’t nothing going to happen.”

Three years before Talley’s murder, Wright broke Officer Bohndan Fylystyn’s nose and jaw with a piece of lumber, also knocking out several teeth.

Despite calls to try Wright as an adult for the assault, Bridge (his public defender) managed to keep his case in juvenile court and secured for his client a sentence that colleagues of Fylystyn no doubt considered too lenient: two years in a wilderness boot-camp program.

It’s unknown if the detectives who questioned Wright in connection with Talley’s murder knew Fylystyn, but breaking a police officer’s face in Philly does not go unnoticed by his brothers.

So it’s almost no wonder that police zeroed in on Wright as a suspect in Talley’s murder before they had even left the crime scene.

Officers testified in 1993 that they received a tip that the man responsible for the murder could be found at a house on the street just behind Talley’s that had recently become a source of drug activity.

Over the next 12 hours homicide detectives would detain and question that home’s owner, Roland Saint James, who admitted to operating a crackhouse on the premises, and his roommate John Richardson. Both men had extensive criminal records, and by their own accounts were heavy crack users. Under questioning each fingered the younger man for Talley’s murder, but their stories varied considerably. For instance, Saint James offered at least three different descriptions of the clothing Wright was wearing the night of the murder.

The two were released within hours of giving their statements and neither was ever charged in connection to the case, despite the fact that Wright’s nine-page confession mentions Saint James and Richardson as accessories to the crime.

Nearly every piece of evidence investigators obtained in building their case against Wright (with the exception of the fraudulent confession) can be traced back to this crackhead duo, who, according to neighbors, expanded their flophouse into a full-fledged drug operation in the months following Talley’s murder. Despite all of that, Judge Byrd ruled that their statements from 1991 can still be used as evidence in Wright’s retrial. (Both men are deceased.)

The prosecution called two other eyewitnesses at Wright’s original trial: Both were teenagers at the time and claimed they saw Wright casing Talley’s house. Both have reportedly recanted their testimony and now say it was coerced. According to reporting on the case last year by Rolling Stone, one of the witnesses said police warned him that he’d never see his mother again if he didn’t testify.

In light of these major evidentiary issues, it’s possible the DA will ultimately drop the case against Wright. A status hearing is scheduled for June, and the trial is slated to resume in August. That gives prosecutors plenty of time to decide that losing graciously is better than doubling down on a potentially grave miscarriage of justice.