Larry Birkhead is honoring his former partner, Anna Nicole Smith, 15 years after her death. The photographer, 49, penned an emotional tribute to Smith on the anniversary of her death on

Instagram on Tuesday, sharing a sweet, candid black-and-white snap of the two from years ago. "Still remembering this one 15 years after her death. She was truly one of a kind. She

struggled for love and acceptance. Just when she found a little piece of one or the other, life seemed to sabotage," Birkhead began. "Today, I remember your heart, your soul and

your beauty, both inside and out," he continued. "Your love is alive still to this day, in the form of a truly one of a kind teenager with her Mom's smile, beauty and

larger-than-life personality who starred on the reality series _The Anna Nicole_ _Show_, was found unresponsive in her hotel room at the Hard Rock Hotel & Casino in Hollywood, Florida

while vacationing with former lover Howard K. Stern in 2007. She was rushed to Memorial Regional Hospital, where she died. She was 39 years old. It was later confirmed that Smith died of an

accidental overdose on prescription medication five months after her and Birkhead's daughter, Dannielynn, was born. Smith's 20-year-old son, Daniel, died of an accidental overdose

in Smith's Bahamas hospital room just three days after the birth of his sister. "You've got to think: My daughter was born on Sept. 7 and on Sept. 10, Daniel died,"

Birkhead previously said. "So you go from that extreme high and low, and how do you process that in your mind? Although her death certificate will list a different cause — an accidental

overdose — in my mind, I think she truly died of a broken heart." RELATED VIDEO: LARRY BIRKHEAD TALKS ABOUT LIFE WITH DANNIELYNN AND HONORS ANNA NICOLE SMITH IN NEW SERIES Smith and

Birkhead's daughter is now 15 years old. In a _20/20_ special that aired in February last year, the father-daughter duo traveled to Mexia, Texas — where Smith grew up — so Dannielynn

could learn more about her mom. "Dannielynn has no idea that she's going to see these things. All this is a surprise," Birkhead said in the special, referring to some of

Smith's personal belongings, including photos, artwork, clothes, and more. "She has a big heart like her mom had, I think she could appreciate these things." "When we

talk about Anna Nicole, there were a lot of happy moments for her. There were a lot of highs before there were a lot of lows," Birkhead continued, adding, "Anna should be

remembered as this larger than life figure that was really a caring, giving person. A beautiful lady who loved her fans and loved her family."