Antonio D’Amico has been haunted by the death of his lover Gianni Versace for 21 years — and he’s now coming forward to share the trauma he endured.

The model and designer participated in the upcoming docu-series airing Monday night on Investigation Discovery (ID) titled “People Magazine Investigates: Crimes of Fashion,” which explores tales of depravity, obsession and betrayal.

Retired Miami police officer George Navarro, retired FBI agent Larry Brukbaker, and retired Miami investigator Steve Wagner also participated in the show.

Versace, who dressed everyone from Madonna to Princess Diana, was shot to death outside his Miami Beach home in 1997 at age 50.

D’Amico recently told People Magazine he vividly heard the gunshots while inside the couple’s villa.

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Antonio D'Amico participated in a new documentary about the life and brutal slaying of his partner, fashion designer Gianni Versace. (ID)

“I heard ‘Bam! Bam!’” said the 59-year-old. “My blood chilled right away.”

Versace had gone out to buy magazines covering recent fashion shows in Paris while D’Amico was getting ready to play tennis when the Italian couture-maker was murdered by 27-year-old Andrew Cunanan.

D’Amico said that despite his wealth and fame, Versace refused to hire bodyguards.

“He thought people looked ridiculous surrounded by these giant men,” said D’Amico. “We never felt in danger. He didn’t want to draw more attention to himself than necessary.”

It was D’Amico who found his partner’s body lying in a pool of blood.

“When I saw the blood I tried to scream, but no sound came out of my mouth,” he admitted.

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Gianni Versace (left) and Antonio D'Amico spent "24 hours a day" together before the designer's sudden death. (ID)

D’Amico caught a glimpse of Cunanan, a man Versace reportedly didn’t know, as he fled.

“The FBI and the police couldn’t find a single person that didn’t like Gianni,” he said. “They couldn’t find a single reason why someone would want to kill him, because he was such a normal guy. He was a very normal, shy person."

About a week later, Cunanan frantically attempted to get a fake passport so he could escape the country. He would take his own life as authorities closed in, ending one of the biggest manhunts at that time.

Versace was one of five victims Cunanan brutally murdered. To this day, his motives remain unknown.

D’Amico said he’s still frustrated that Cunanan’s motive for killing Versace was never made clear. And his memory of what he witnessed and heard that day is one he can never forget.

“I would often ask myself in the aftermath whether things would have been different had I been there with him that morning,” he said. “Would something have changed? Could I have protected him? Could I have saved him?”

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Gianni Versace. (ID)

D’Amico said after Versace’s death, he fell into “a black pit,” and suffered from a severe depression that lasted for eight years.

“When Gianni died, I was cut in two,” he shared.

But after years of grieving, D’Amico realized he needed to move on and find happiness without Versace.

“Of course, I never forgot. But I took my life in my hands and I started over again,” he said.

D’Amico currently lives in Milan with his partner of 13 years, Alberto Santinelli. He has had no contact with the Versace family after he settled a dispute over Versace’s will in 1998.

He revealed throwing himself into work also helped him cope with the loss.

“My work was instrumental, fundamental for this,” said D’Amico. “It helped me put aside all the pain, the grief and forget for a moment in a bid to have a new objective.”

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Gianni Versace (ID)

D’Amico hopes the documentary will also show audiences a new side to the sought-after designer to the stars.

He chose to remember not the style icon, but the man who often had “his head in the clouds.” He described Versace as messy, often forgetful, a homebody and a terrible cook — despite coming from an Italian region famous for its cuisine.

The couple spent “24 hours a day” together jet-setting between Versace’s homes in Milan, Lake Como, New York and Miami Beach.

“Gianni, he paid attention to the people around him,” said D’Amico in an exclusive clip of the documentary obtained by Fox News. “Every time someone needs something, he was ready to help.”

The couple met in 1982 and were together until Versace’s death.

“Gianni was one of the most creative people in the fashion world,” said D’Amico. “But as a person, he was the sweetest man in the world.”

The season finale of "People Magazine Investigates: Crimes of Fashion" airs Monday, July 30 at 9 p.m. on Investigation Discovery (ID).