Aaron Carter 'Never Really Dealt with a Lot of Trauma' from Sister and Father's Deaths, Says Source

In the decade leading up to his own death at age 34 on Saturday, Aaron Carter lost multiple immediate family members to various causes, and his struggle with substance abuse worsened in the aftermath, sources close to the late pop star and rapper tell PEOPLE.

"Aaron never really dealt with a lot of trauma he had," says the insider, referencing Aaron's older sister Leslie, who died at age 25 of an overdose in 2012, and father Robert, who died at age 65 of a supposed heart attack (according to TMZ) in 2017. "He was really torn up when Leslie died, but it was Bob's death that really threw him."

The source continues, "He had such a dysfunctional relationship with both parents, but something about losing his dad really threw him. That's when I saw him really start to spiral. He had gotten in trouble before, but he went from a partier to something a lot more dark then. It was like he gave up."

Ron Galella, Ltd./Ron Galella Collection via Getty Aaron and Robert Carter

Aaron was discovered Saturday morning at his house in Lancaster, California, according to TMZ, who first reported the news. A spokesperson for the Los Angeles County Sheriff's Department told PEOPLE a body was discovered just before 11 a.m., but police did not officially identify the victim.

Police sources tell PEOPLE the star was found by a house sitter in his bathtub, and that there were prescription pills and drug paraphernalia in his bedroom. Though a cause of death has not yet been determined, the police sources believe he lost consciousness and drowned.

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The star faced legal troubles and struggled with addiction over the years, for which he sought treatment. Most recently, he was pulled over for suspicion of DUI on Tuesday, but officers found that he wasn't under the influence after conducting a field sobriety test, TMZ reported.

Evan Agostini/ImageDirect, Kristy Leibowitz/Getty, Gabe Ginsberg/Getty Robert, Leslie and Aaron Carter

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Another source close to Aaron tells PEOPLE that he didn't have a strong support system prior to his death. "He had no one he could trust, and no one trusted him. He was spiraling out of control and he knew it," says the insider. "It was sad to watch. It was actually painful to see him make the choices he made."

Michael Tran/FilmMagic Leslie and Aaron Carter

Shortly after his death was confirmed, Aaron's twin sister Angel posted an Instagram tribute to the "I Want Candy" singer alongside family photos of the pair as babies and young children. "To my twin… I loved you beyond measure. You will be missed dearly," she began. "My funny, sweet Aaron, I have so many memories of you ... and I promise to cherish them."

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Angel added: "I know you're at peace now. I will carry you with me until the day I die and get to see you again. 💔."

In addition to Angel and Leslie, Aaron was also a sibling to brother Nick Carter and sister Bobbie Jean Carter, as well as half-sister Virginia Marie Carter, half-brother Kaden Brent Carter, and step-sister Taelyn Dobson.

RELATED: Nick Carter and Backstreet Boys Tearfully Honor Aaron Carter at London Concert: 'Heavy Hearts'

During a Backstreet Boys concert in London on Sunday, Nick, 42, and the group honored his brother's memory onstage. Midway through the show, singer Kevin Richardson told the crowd at the O2 Arena: "Tonight we got a little bit of heavy hearts because we lost one of our family members yesterday."

"We just wanted to find a moment in our show to recognize that Nick's little brother, Aaron Carter, passed away yesterday at 34 years old," added Richardson, 51. "He was a part of our family and we thank you guys for all the love and all the well wishes and all the support."

In footage posted on the Theatre website All That Dazzles, Nick then became emotional. In response, bandmates AJ McLean, Howie Dorough and Brian Littrell rushed over to embrace him — with Littrell offering his sleeve for Carter to wipe his eyes.

"We'd like to dedicate this next song to our little brother Aaron Carter. You will be missed brother," Dorough announced before the band launched into "Breathe."

Elsewhere during the show, a montage of Nick and Aaron in different stages of their lives was shown on a screen during the song "No Place." This eventually settled on a solo shot of Aaron, with "Aaron Carter 1987-2022" shown in large text.

If you or someone you know is struggling with substance abuse, please contact the SAMHSA helpline at 1-800-662-HELP.