An undated file combo image shows brothers Erik and Lyle Menendez, who were convicted March 20, 1996 of the first-degree murder of their wealthy Beverly Hills parents. The brothers were sentenced to life imprisonment. Reuters

About 27 years have passed since the Menendez brothers killed their parents, but ABC News is reopening and diving into their sordid story this week. The network was set to air "Truth and Lies: The Menendez Brothers," a two-hour documentary special on the infamous case, Thursday at 9 p.m. EST.

It was August 1989 when Erik and Lyle Menendez, then aged 18 and 21 years, respectively, ended the lives of their parents, Cuban-American entertainment executive Jose Menendez and his wife, Kitty. The wealthy family resided in a mansion in Beverly Hills, California, and that's where the crime took place.

The two brothers used shotguns to kill their parents in their home in what prosecutors claimed was a decision motivated by greed. Authorities believed the brothers carried out the murders because they wanted roughly $15 million in inheritance money.

But recently, Lyle Menendez spoke to ABC News about how the events shaped his life.

“It’s shocking to think … that I could have been involved in taking anyone’s life — and my parents’ life … it seems unimaginable because it seems so far removed from who I am,” Lyle Menendez told the news outlet.

Ahead of the documentary’s premiere, here are eight things to know about the Menendez brothers' case.

1. Since the sentencing in the '90s, Lyle and Erik Menendez have not seen one another. But they write to one another, according to "The Today Show."

2. Craig Cignarelli, a friend of Erik Menendez’s and a high school classmate, wrote a screenplay when the two were young that followed the eerie story of a well-to-do man who kills his parents for money. After the murder, Erik Menendez told Cignarelli what he did. Cignarelli told ABC News he went to the police after the admission.

3. In 1993, Lyle Menendez testified in court that the boys’ father and mother had sexually abused them. That offered up another motive for the murders.

4. Right after the crimes, investigators did not entertain the boys as suspects. The pair were not arrested until months into the investigation and seven years before they would be convicted, according to "The Today Show."

5. The first trial was deadlocked after a matter of weeks and was pronounced a mistrial in 1994. Prosecutors claimed the killings were done for money, and defense attorneys argued they were the result of a lifetime of abuse the boys experienced by their parents.

6. Both brothers were eventually given life sentences with no parole in 1996.

7. Lyle and Erik Menendez both married while in prison. Lyle Menendez is with his second wife.

8. Erik eventually started a hospice program at his state prison in Ione, California.