Lisa Marie Presley penned a heartbreaking tribute to her late son, Benjamin Keough, on what would have been his 28th birthday Wednesday.

Keough died on July 12 at age 27. The Los Angeles County Medical Examiner-Coroner's Office confirmed that he died by suicide.

Calling Keough "my beautiful beautiful angel," Presley, the daughter of Elvis Presley, began her note, "I worshipped the ground you walked on, on this earth and now in Heaven. My heart and soul went with you."

"The depth of the pain is suffocating and bottomless without you every moment of every day. I will never be the same," she continued. "Happy Birthday my sweet sweet Boy. You were much too good for this world."

In the aftermath of Keough's death, his 31-year-old sister, actress Riley Keough, has posted on Instagram multiple times about her family's loss, calling her brother in August, "Love of my life." On Wednesday, she shared a series of photos and captioned them, "Happy Birthday beautiful angel."

Benjamin Keough was a relatively private individual, though he did appear in the 2005 documentary "Elvis by the Presleys." He also participated in the music video of his mother's 2012 duet with his late grandfather, "I Love You Because."

He is survived by his mother and sister, as well as his father, musician Danny Keough, and his 11-year-old twin siblings, Harper and Finley Lockwood.

"Please wait for me my love, and hold my hand while I stay to continue to protect and raise your little sisters and to be here for Riley," Presley wrote in her message Wednesday. "I know you would want that."

If you or someone you know is in crisis, call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) or contact the Crisis Text Line by texting HOME to 741741.