NEW YORK — (NEW YORK) -- Brandon Woodruff had appeared to live the normal life of a 19-year-old, small-town Texas kid - but that changed in 2005, when both of his parents were brutally murdered. After an investigation, Woodruff was charged with capital murder, found guilty and sentenced to life in prison.

Now, Woodruff has served 13 years of his life sentence and said he’s finally ready to share his story in the first interview after his conviction.

“I’m innocent. I did not kill my parents at all,” Woodruff told “20/20” in an interview. “I think that you should look at the totality of the evidence.”

Woodruff grew up in a community outside of Dallas with his mother Norma Woodruff, father Dennis Woodruff and older sister Charla Woodruff.

Watch the full story on "20/20" FRIDAY at 9 p.m. ET on ABC.

Growing up, former high school classmates said they remember Woodruff as a popular, outgoing, animal lover who was the president of the Future Farmers of America. The teen was voted most school spirit and had a steady girlfriend.

But during the investigation of his parents' murders, authorities discovered that while Woodruff attended Abilene Christian University, he would go dancing at gay clubs, was dating men and had even traveled out of state to participate in adult movies.

On Sunday October 16, 2005, Woodruff visited his parents at their new home in Royse City, Texas. The couple was downsizing to help pay college tuition for their two children. He told police he left after the family enjoyed a pizza dinner together. Woodruff was the last known person to see both of them alive.

Two days later, Dennis and Norma Woodruff were found murdered in their new home. According to authorities, Dennis Woodruff was found shot once and stabbed nine times. Norma Woodruff sustained multiple gunshot wounds and had her neck slashed, investigators said.

Police concluded that Norma and Dennis Woodruff must have likely been killed sometime between 9 p.m. to 11 p.m. Sunday night. However, the medical examiner was not able to confirm the time of death. Norma Woodruff's last phone conversation was with her mother around 9 p.m. and the next person to try and contact the couple was Charla Woodruff, who was at college in Arkansas, just after 11 p.m. Charla Woodruff was unable to reach them. When Woodruff was questioned by police about his whereabouts that night, there were inconsistencies in his timeline.

Michelle Lee, the mother of Woodruff's girlfriend, also contacted law enforcement to report that a gun and bullets were missing from her home. Woodruff had been in her home the weekend before his parents were found dead. Investigators compared a bullet found at the crime scene with a bullet from the Lee home and said they believed they were consistent. The Lee's gun was never found, but investigators believe it was the same caliber as the weapon used in the crime. A murder weapon was never recovered and Woodruff denies stealing the gun.

Woodruff was arrested and charged with capital murder.

In June 2008, a family member found a dagger in the barn of the Woodruff’s old house in Heath, Texas. Dennis Woodruff’s blood was on this weapon. Brandon Woodruff’s former college roommate testified that dagger was the same one Woodruff had in his dorm room. Authorities could not conclude if the dagger found was the murder weapon and Woodruff denies that the weapon is his.

Woodruff’s grandmother Bonnie Woodruff has supported Woodruff from the beginning and still maintains her grandson is innocent.

“I know Brandon was wrongfully judged. And murder? Now I know Brandon didn't do that. Someone else is letting him take the blame for it,” said Bonnie Woodruff.

Over the past decade, advocates for Woodruff say there are red flags surrounding the investigation and his subsequent trial. Woodruff claims his sexuality played a role in his arrest and conviction.

“I do believe that that’s a major factor. I felt like the investigators were able to use that. They would say, well, ‘Did you know that he was dancing in gay bars? Did you know he had a boyfriend, did you know?'” said Woodruff.

During the investigation, police told friends and family of Woodruff that they "don't care" if he is gay.

During jury selection, eight out of twelve jurors told the court that they believed homosexuality was morally wrong, but they were still allowed to serve on the jury after promising the court they could be fair toward Woodruff.

“Guess what? In 2005 people still felt that homosexuality was immoral because eight of the 12 jurors on Brandon's case specifically said it was immoral,” said Philip Crawford, the author of a book called "Railroaded" about Woodruff's case.

ABC News spoke with several jurors who said Woodruff’s sexuality wasn’t a factor in the jury's decision.

While in prison, supporters have started a movement to free Brandon and now the Innocence Project of Texas has taken his case.

Allison Clayton, the deputy director with the Innocence Project of Texas claims that the prosecution’s case against Woodruff relied heavily on a timeline because they say Woodruff's whereabouts were not accounted for at the time that authorities estimate the couple was killed. Clayton points to cell phone records that would further compress the window of opportunity to commit the murders.

“Brandon kills his parents in, what? the most, 19 minutes? He has to act fast or he is taking calls during the course of committing these murders,” said Clayton. “That's the only way the timeline makes sense, that he does something to one of his parents, and then takes a call and chats with [a friend] like nothing's wrong.”

In addition to the timeline, Clayton said one of the other biggest potential breakthroughs for this case would be taking DNA evidence from hair found in Norma Woodruff’s hand.

“In Norma's hand, police found a clump of longer blonde hairs. Now, that would normally be an indicator that she had somehow grabbed her attacker and that she pulled his or her hair,” said Clayton. “Law enforcement never tested that hair. And one of the things that we've been fighting for in the case is trying to figure out who has that hair because we want it tested.”

In 2000, Woodruff’s direct appeal to the state was denied. In order for Woodruff to be released, he needs to prove to the Texas Court of Criminal Appeals that he is innocent.

“As it stands right now, if we don't have a break in the case, then there's nothing we can do for Brandon,” said Clayton. “He is going to be in prison for the rest of his life, but maybe there will be evidence that can help him, maybe someone is out there, who knows something, who's willing to step forward.”

Bonnie Woodruff said that she still hopes that one day she can hug her grandson again and tell him “he’s home now.”

​​”We are all still a family unit and we all love one another. People can live with what they think, I can live with what I think because I know the truth and the truth's gonna come out,” said Bonnie Woodruff.

Woodruff said he won’t stop fighting to prove his innocence.

“I'm not gonna stop. I'm gonna keep fighting and I'm gonna keep fighting to prove my innocence,” he said. “I do believe in my heart that it will happen."

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