Amy Gellert was fatally stabbed by a masked man in the driveway of her family's home in Cocoa Beach, Florida, more than 23 years ago
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Credit: Karl Ronstrom

Amy Gellert had just returned from church and pulled into the driveway of her family’s home in Cocoa Beach, Florida, on March 20, 1994, when a nightmare unfolded with savage fury.

As Gellert stepped out of her car, her stepfather, Bob Lehton, sprinted from the front door of their house — drenched in blood. Running behind him was a man in a black ski mask clutching a dagger and a gun.

The attacker had already stabbed both Lehton and Gellert’s mother, Bunny, and was now headed straight for Gellert, 21, slashing her before fleeing.

By the time police arrived minutes later, Gellert had stumbled to the parking lot of a nearby apartment complex and died. Her parents, who spent weeks in the hospital, miraculously survived.

“Not a day goes by,” Gellert’s older brother Mark tells PEOPLE in this week’s issue, on newsstands now, “when we don’t think about Amy.”

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Credit: Brevard County Sheriff's Office

Now, more than 23 years later, investigators in Florida are pushing to heat up the case that went cold years ago.

They have two clues and two suspects — and they’re hoping somebody in the public may know something that will give them the break for which they’ve been searching.

“The right information could break this case open,” says Tod Goodyear, one of the original investigators with the Brevard County Sheriff’s Office.

• For more on the 23-year-old murder-mystery, subscribe now to PEOPLE or pick up this week’s issue, on newsstands now.

The killer, who fled with cash and credit cards, left behind precious little evidence, in terms of fingerprints or DNA.

But during his attack on Amy, the man dropped the magazine from his pistol, which detectives quickly linked to a prop gun used in movies and theater productions.

Police also have a partial sketch of the dagger Amy’s parents described being stabbed with, which features an “ornate” hilt.

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Credit: Brevard County Sheriff's Office

After working their way through a dozen people who police initially believed could be responsible for the killing, cold case detectives say they have two “main suspects” — Dominic Kanuika, a short-order cook who had just moved to the area, and Scott Manley, who canceled a get-together with Amy on the night she was killed.

Neither of the men, whom police say are in prison on unrelated crimes, has been charged in connection with Amy’s death.

The passage of time, Goodyear says, can both help and hurt a criminal investigation.

“Memories start to fade a bit with time,” he says. “But relationships also fall apart with time, and people may come forward who wouldn’t have come forward at the time because of the relationship they had with the suspect.”

Anyone with information is urged to call the Brevard County Sheriff’s Office at 321-633-8413.