Conroy Dyson unfolded his white cane until the tip hit the floor, then slowly made his way into a D.C. courtroom one recent afternoon. It had been more than four decades since he was convicted of breaking into a congressional staffer's Capitol Hill home and sexually assaulting her.

After his arrest, and in the decades that followed, Dyson has maintained his innocence in the vicious 1975 attack. His first trial ended in a hung jury, but a second jury found him guilty. He spent years in prison.

Now, with his eyesight failing and his health declining, the 66-year-old Dyson said he wants to clear his name before his dies.

"I am not guilty. I did more than eight years for a crime I did not commit," Dyson said during the hearing last month in D.C. Superior Court.

Dyson's attorneys contend that their client was a victim of misidentification and flawed investigative techniques that although common in the 1970s have since been questioned. They claim the lineup used by police was biased and say testimony regarding hair and fiber analysis was faulty.

But the woman who was attacked remains certain that she correctly identified Dyson. Joan M. Burda said she focused on the rapist's face during the nearly 40-minute assault, which still haunts her today. The Washington Post does not generally identify victims of sexual assault, but Burda agreed to have her name used.

"He waits 42 years later to raise this. He's wrong," Burda said in an interview from her Ohio home. "He was on top of me. I studied his face. I kept staring at him. I know it was him. I was not wrong."

Challenging the evidence

In the spring of 1975, Dyson was arrested for breaking into a Southeast Washington home and stealing a TV. He was sitting in a police station when an officer pulled a sketch of a man off a bulletin board, walked over and held it near Dyson's face.

The image, made by a police artist, was based on Burda's description of the stranger who climbed a fire escape and slipped into her apartment through an open window. Dyson became a suspect in the rape.

In their petition for exoneration, Dyson's attorneys did not suggest another suspect or reveal any new DNA evidence. It is impossible to know what ­modern-day DNA tests would have shown because all evidence collected by police has been discarded.

The H. Carl Moultrie Courthouse is a courthouse of the Superior Court of the District of Columbia located at 500 Indiana Avenue NW, Washington, DC. (Keith Alexander/TWP)

Instead, the attorneys argue that from the moment police focused on Dyson, there were problems with the investigation.

Last month, during two days of hearings before Judge Robert D. Okun, Dyson's attorneys Jason Tulley and Emily Voshell identified several factors which they say led to the wrong man.

Burda told police her attacker was clean-shaven and about 5 feet 6 inches or 5 feet 7 inches tall. Arrest records show Dyson is 5 feet 8 inches tall. But Dyson's attorneys said their client was placed in a lineup with men who had facial hair and who were much taller than he — making him stand out.

The attorneys said D.C. police — who were under intense scrutiny to solve numerous sexual attacks in the District — may have inadvertently influenced Burda to pick someone out of that lineup. When she arrived at police headquarters to view the men, the lawyers said, an officer told her someone had been arrested. Dyson's attorneys say that information convinced Burda the attacker must have been in that group.

Dyson's attorneys noted that the attack happened about midnight in a bedroom lit by only an outside streetlight and a hallway light, conditions they said would have made it difficult to clearly see a face.

They also say that Burda, in addition to being terrorized by the assault, misidentified her attacker due to cross-racial biases. Dyson is black and Burda is white.

Eyewitnesses, especially those who are also victims, the attorneys say, have a harder time identifying people who are of a different racial background. ­Dyson's legal team cited a study by the National Academy of Sciences that found cross-racial misidentifications made up 42 percent of DNA exonerations in which eyewitness identifications were made.

Dyson's attorneys also point to what they say was flawed forensic analysis presented at trial.

An FBI analyst who compared Dyson's hair with hairs found in Burda's bedroom testified that they differed in "as many as seven of 15 characteristics," the attorneys wrote in their filings. Although the analyst testified he couldn't conclude one way or another whether the crime-scene hairs were Dyson's, Dyson's attorneys say the results point "emphatically" away from their client.

Dyson's attorneys also questioned an analyst's testimony that fibers found on Burda's bed were "like" those from a wool peacoat Dyson owned. The lawyers questioned the precision of the analysis, conducted with a microscope and the naked eye.

Dyson's attorneys said the FBI has updated its practices and that such testimony would not be allowed today.

'He was the one'

At the time of the attack, Burda, then 22, was an assistant to Rep. J. Edward Roush ­(D-Ind.). The man who sneaked into her apartment wrapped his hands around her throat and threatened to kill her if she screamed.

Burda, now 65, says she has tried to place the details of that night "in a closed box." But the recent phone calls from Dyson's attorneys alerting her to Dyson's exoneration efforts forced that box open.

"They said I couldn't tell the difference between one black man and another. That people make mistakes," Burda said. "But I did not make a mistake. I am positive he was the one."

That night is etched in her memory. "His face was inches from mine," Burda recalled. "He was laying on top of me. I saw his face. I studied his face."

Prosecutors are fighting Dyson's bid for exoneration. They say he was Burda's attacker and that his attorneys provide no new evidence to support their claims.

An attorney with the District's Public Defender Service sent Burda a book written by a rape victim, a white woman, who identified the wrong man as her assailant. Her attacker was black.

Burda threw it away.

'Nothing to do with it'

During the recent hearings, Dyson's attorneys called experts who testified there were problems with the police lineup and the FBI analysis. Dyson also took the stand, something he did not do during his trials.

"I'm not trying to be disrespectful," Dyson said, his voice growing louder to questions from prosecutor Pamela Satterfield. "But it's been 40 years and I'm just tired. I'm seriously tired. I'm sick of dealing with this for something I did not do."

Dyson testified Burda "made a mistake" when she picked him out of the lineup and twice pointed at him as her attacker in court.

His then-fiancee and sister testified at the trials that Dyson was with the fiancee smoking marijuana when Burda was attacked.

In 1986, when Dyson was up for parole,his attorneys note, he refused to admit his guilt in an effort to qualify for early release. So Dyson took a lie-detector test. His attorneys say it indicated he was being truthful.

Since his release from prison, Dyson, who lives in Southeast, has struggled. He has been arrested for simple assault and stealing clothes and cigarettes.

For years, he worked at Howard University coordinating the school's food preparation unit. But as his eyesight worsened, Dyson testified, he was unable to navigate the busy department and lost that job. He now stocks shelves at a D.C. crafts store.

"For 40 years this has been hanging over my head and I had nothing to do with it," Dyson said. "And I want everyone to know it."

Prosecutors and Dyson's attorneys have until Dec. 1 to file additional paperwork. Okun could reject Dyson's bid, decide Dyson should be exonerated, or order a new trial.

Julie Tate contributed to this report.