Lucy Tsoeu, 46, says slamming doors and the clacking of a typewriter at night have led her to believe a ghost is hanging about.

Shortly after nightfall, flashlight in hand, Rivas Bright knocks twice on the broken window of an abandoned building in Pretoria.

“Still!” he tells his fellow ghost hunters. They hold their breath, waiting for a response from the shadows.

It’s been about two years since Bright, 39, set up Upsidedown, a group of paranormal enthusiasts hunting ghosts in a bid to prove they are real.

It’s a daunting task, given spirits are proverbially evasive.

“It’s a broken science,” Nigel Mullinder, 29, a member of the team and a casino worker by day, says of the study of paranormal events, which has drawn the interest of researchers and parapsychologists, but produced little hard evidence.

Bright and his team of “sceptical believers” – five men and two women – have turned to tech to solve the mystery.

Armed with an arsenal of tools including infrared cameras, motion and heat detectors, radios, and a self-developed app to uncover paranormal activity, they scout alleged haunted buildings looking for clues in cavernous hallways and rusting stairwells.

“[We] need a set of evidence that would allow us to prove that it’s not just the wind [blowing] through the window or a door closing because of some sorts of vibrations,” says Mullinder.

Ghost hanging about

This time, they came to an abandoned building on the campus of one of SA’s largest universities, which asked not to be named. Night guards here have been spooked by creepy noises.

Lucy Tsoeu, 46, says slamming doors and the clacking of a typewriter at night have led her to believe a ghost is hanging about.

Her colleague, Mpho Mthombeni, 30, says he has heard toilets flush and felt a strange presence when there was no one about.

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“Maybe [ghost hunters] be able to cool them down,” Tsoeu says, half worried, half excited.

Since Bright – a retail chain store employee – founded Upsidedown, the group has gathered a few thousand followers on social media, spent several thousand rands on equipment and searched about a dozen premises, following tip-offs.

Spirits of children

At the university building, the group checks every room, placing their detecting tools on a floor covered with dead leaves.

“We are literally a bunch of guys that stand in the dark, ask questions … and follow red and green blinking lights,” he quips.

Bright rings a bell to signal to the ghosts that he wants to talk to them – but there is no reply.

“We are not here to hurt anybody or remove you from that place. All we’re looking for is answers,” he says.

Gunshots echo in the distance in a city known for its high levels of crime.

“Did you hear that? I could clearly hear someone call my name,” says a member of the team. It’s hard to corroborate.

As the hunt goes on, others in turn sense a movement or hear a sigh.

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The group of white, middle-class South Africans had been to this building a month before.

Then, its members say, they communicated with the spirits of children in a room that was used as a makeshift morgue during violent riots in the 1980s.

Mullinder tries to get in touch again, listening to a radio frequency meter while blindfolded.

Everything is filmed to capture potential evidence. But the result is inconclusive.

“I can understand why people would think we are crazy, but when we finally get that massive piece of evidence … who’s the crazy one then?” says Bright.