"Today is going to be a tough one for me but I know your daddy is playing birthday songs for you up in heaven," she wrote. "I love you baby boy!!!"
The "I Want Candy" singer was found dead in his bathroom on Saturday, November 5, near prescription pill bottles and compressed air canisters. His frantic housekeeper called emergency services after discovering him unresponsive in the tub, and he was later pronounced dead. Homicide detectives also arrived at the scene, but it's been reported they found no evidence of foul play.
Later that day, Martin was photographed just outside of his property looking grief-stricken as she tearfully hugged friends and spoke with police officers.
"We are extremely saddened and shocked to confirm the passing of Aaron Carter today," his rep confirmed in a statement shortly after news of Carter's death hit headlines. "At the moment his cause of death is being investigated. We ask that you give the family time and they will have more information when available. We cannot express the outpouring of love coming in."
As OK! previously reported, despite lawyers urging him to draw up the paperwork, Carter passed away without a final will and testament in place.
It is currently up to the State of California to make the final determination on who will inherit his estate. However, according to California law, because Carter was not married at the time of his death, it is likely that any of the singer's assets will be awarded to Prince, who was his only child.