Visitors to Amsterdam’s famous red-light district this week will see a startling new face among the brothel windows and displays that line the streets: a life-size hologram of a 19-year-old woman, sitting on a stool and peering out at passersby to ask them for help.

That is how Dutch police are appealing to the public to help solve the murder of a sex worker that has puzzled them for over 15 years.

In 2009, Bernadett “Betty” Szabó, whose likeness is depicted in the hologram, was found dead in her workroom in the red-light district lying in a pool of blood, according to the Dutch National Police. She had been stabbed dozens of times. Investigators couldn’t solve the murder and Szabó’s death became a cold case, police said.

Over a decade later, Dutch investigators are convinced that witnesses who could shed light on the murder are still out there. It spurred them to launch a new awareness campaign for Szabó’s murder, police announced Friday, headlined by a hologram of the murder victim asking the Amsterdam public to help solve her own case. The police force contacted Szabó’s relatives before producing the computer visualization, it said.

“This is the first time we do something like this and, to be honest, we’re a bit nervous,” Benjamin van Gogh, coordinator of the Dutch police’s Amsterdam Wanted and Missing Persons Team, said in a news release. “We want to do justice to Betty, to her family and friends, and to the case.”

Szabó grew up in poverty in Hungary and moved to Amsterdam to work as a sex worker when she turned 18, according to a file on her case on the Dutch National Police’s website. She worked in De Wallen, the city’s largest and most famous red-light district, where brothels can legally operate.

Two co-workers found Szabó dead in a workroom in February 2009. She had given birth to a son months earlier.

“Although, of course, every murder case is terrible, Betty’s story is particularly poignant in a number of ways,” said Anne Dreijer-Heemskerk, an investigator with the Dutch police. “A young girl, just turned nineteen, who was robbed of her life in a horrible way. And who didn’t have an easy life before she died.”

Investigators interviewed witnesses and reviewed security footage but were ultimately unable to solve Szabó’s murder, according to Dutch police. But they are still hopeful that someone among Amsterdam’s population — or the millions who pass through the city, one of Europe’s most popular tourist destinations, every year – has information that could point to a culprit.

“Betty was murdered in one of the busiest areas in Amsterdam, maybe even in the Netherlands,” Dreijer-Heemskerk said. “It is really almost impossible that there are no people who saw or heard something unusual at the time.”

For the outreach, Amsterdam police made the holographic representation of Szabó using 3D visualization technology, something they have not used before, according to the news release.

Dutch police also set up screens on a house in the red-light district that display descriptions of Szabó, her background and her death, images of Szabó and a documentary about her case, according to the news release. Next to them, another screen shows Szabó’s life-size hologram, sitting and gazing out at the red-light district like she might have when she was alive.

The hologram of Szabó occasionally gestures to passersby and appears to approach the glass of the screen. When it does, the holographic Szabó breathes on the glass, causing it to appear to fog up and reveal a handwritten message: “help.”

“It is difficult to determine what it takes to get possible witnesses in this case to share their information with us,” said van Gogh. ” … In this type of case, we always try to put a face on a victim, so that informants know who they’re doing it for, and the hologram is a way of taking this a step further.”

The displays will be up in the red-light district until Nov. 15, according to the Dutch police’s news release. Investigators are offering a reward of around $30,000 for information in her case.

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