Lyle Menendez and his wife, Rebecca Sneed, quietly ended their marriage after more than 21 years together, but she remains a key figure in his life despite rumors of a cheating scandal Sneed says are baseless, PEOPLE has learned.

The couple tied the knot in 2003 while Menendez was serving time for the 1989 murders of his and his brother Erik's parents.

Lyle Menendez, 56, is just moving on fast from behind bars. The infamous prisoner, who was convicted in 1996 alongside his brother, Erik Menendez, for the 1989 double murders of their parents, Jose and Kitty Menendez,

Lyle Menendez’s wife Rebecca Sneed announced she and the 56-year-old—in prison for murdering his parents—are separated. The news comes amid possible resentencing for Lyle and brother Erik.

Rebecca Sneed, the wife of convicted murderer Lyle Menendez, has confirmed that the couple has been separated for some time. In a Facebook post on Friday, Sneed clarified that while they are no longer together, they continue to maintain a close relationship, referring to themselves as "best friends and family."

The wife of convicted killer Lyle Menendez slammed the decision to delay a resentencing hearing for her husband and his brother Erik Menendez until late January. “Tomorrow will be the guys’ 35th Thanksgiving in prison. Next month will be their 35th Christmas in prison,” Rebecca Sneed wrote Wednesday on a Facebook page dedicated to Lyle.

Lyle Menendez is reportedly now dating a 21-year-old British college student after ending his more than two-decade-long marriage to Rebecca Sneed.

Lyle Menendez, a focus of "Monsters" season two, was first married to Anna Eriksson. They divorced and he later married Rebecca Sneed.