A sad day for Danielle Riley Keough: her only brother shot himself after a party for her husband and Benjamin’s girlfriend.

The only grandson of the late music icon Elvis Presley was at his mother Lisa Marie Presley‘s home in Calabasas on July 12 when he shot himself in a bathroom early that Sunday morning. Diana Pinto, the late 27-year-old’s girlfriend, shares a birthday with Ben Smith-Petersen, the husband of Benjamin’s “twin soul” sister Riley Keough. Apparently both were being celebrated in a joint party on Saturday.

While it’s unclear what led to Keough’s tragic passing, it has been reported that a woman, believed to be Pinto, was heard screaming “don’t do it” around 3:30 a.m. by neighbors.

After police arrived on the scene around 6 a.m., a neighbor heard officers interviewing a bereaved woman, also believed to be Pinto, saying she was worried the family would “hate” her, and she would be blamed for his death.

A full autopsy was completed the day after his death by the Los Angeles County Department of Medical Examiner-Coroner‘s office, which determined his cause of death to be an “intraoral shotgun wound,” officially ruled as a death by suicide.

This report comes after a heartfelt tribute was posted by his girlfriend Diana on Sunday, one week after his death. Accompanied by several photos of and with her late love, she wrote in part (below) on Instagram:

“You are my whole world and my whole life, you live with me now every day in my heart, in my soul and in my mind. My travel partner. My best friend. I will cherish all the memories we’ve made together and keep them close to my heart. I feel your silliness within me still making me laugh. Every second of every day I think of you, now I know the true meaning of grief. Please give me strength to keep going because I don’t know how I’m supposed to do this life without you.

You will always be the love of my life, my everything.”