Aaron Carter continues to lambast his brother, Backstreet Boys member Nick Carter, after the latter issued him a restraining order. The battle came to a head on Sunday, when Aaron took to social media and accused Nick of raping a 91-year-old woman.

The "I'm All About You" singer claimed that his older brother raped the woman, named Mildred. She was one of the elderly women under their mother's care in hospice. Nick allegedly covered her mouth so no one would hear her scream.

Aaron said his brother even admitted to the deed in confidence in his pickup truck. He added that their mother knows about what happened.

The 31-year-old "I Want Candy" hitmaker even asked the FBI to investigate Nick on these claims. He offered to be put under a lie detector test to prove that he is telling the truth. He also asked the feds to put Nick on the test.

"Mildred and opal who my mother was keeping alive. [FBI] what are you gonna do about that!? NOTHING!? I'm REPORTING A RAPE FROM NICK ON SN ELDERLY WOMEN WHO WAS DYING AND WAS 91 that he raped. Strap nick up to a polygraph machine and a really good one please [sic]," Aaron wrote on Instagram.

Aaron shared this accusation against his brother alongside a clip of the family's 2006 reality TV show, "House of Carters." The video shows Nick and Aaron in a tense argument with the former seemingly threatening his younger brother.

Aaron's allegations came after Nick filed a restraining order against him for statements he allegedly made about having thoughts of killing Nick's pregnant wife and their unborn child. Aaron clarified that he never meant any harm to anyone, especially not his family.

Likewise, he said that he and his brother have never been close. They have not seen each other for four years and that Nick always bullied him when they were young. Aaron claimed the restraining order was Nick's way to shut him up for supporting the women who came forward with their rape accusations against the BSB singer.

Amid Aaron's accusations, Nick has remained mum on social media. His fans continue to express their support. Meanwhile, Aaron also has his own army supporting him in his allegations.

Singers and brothers Nick (L) and Aaron Carter answer questions about their new reality television program 'House of Carters' which features them and their three sisters on E! Networks during a session at a Cable Television Critics Association p
Singers and brothers Nick (L) and Aaron Carter answer questions about their new reality television program 'House of Carters' which features them and their three sisters on E! Networks during a session at a Cable Television Critics Association press tour in Pasadena, California July 11, 2006. Reuters