Photographer Khiang Hei remembers the days around January 7, 1979, on the dusty fringes of Sisophon – tanks slid down National Highway 5 and an artillery shell hit a nearby mountain.

He was about 12-years-old and scared – fear permeated the Khmer Rouge work camp where he was as the regime crumpled. The people there had no idea who was directing the gunfire and whether they were in danger.

Seyha, lost in Tuol Sleng Museum: one of the paintings on show. Photograph: Thang Sothea/Phnom Penh Post

“All of the kids split into different groups – some followed the Khmer Rouge into the jungle while the majority fled to find their families.”

Khiang was one of the latter, and after finding his parents and sister, the family made the pilgrimage back to their home of Phnom Penh before escaping as refugees to Vietnam and, later, New York.

Today is Victory Day, marking the 34th anniversary since some 150,000 Vietnamese troops rolled into the abandoned capital, ending the four years of Pol Pot’s dictatorship.

Khieng, now a 44-year-old photographer, who documented the Tiananmen Square uprising in 1989, has now donated one of his recent collections to a tribute exhibition for the late Vann Nath: the revered painter, human rights defender and S-21 survivor – one of just seven – whose vivid paintings and recollections of the torture centre now line its walls.

The photo shows swathes of tangled kaleidoscopic electric cables and power lines strewn across Phnom Penh’s streets: it’s a symbol of Khiang’s return to the city in mid-January 1979.

“To me those powerlines symbolise the state of things then. The city was torn apart and they had to rebuild, but they didn’t know how.

“There was no proper planning, so what we see now is a mess. When I was a refugee I remember seeing coloured lines guiding you everywhere, like in hospitals.”

The electrical cables are also symbolic of a memory of that time seared into his mind – walking the empty streets near Tuol Sleng in January 1979 he found the disfigured body of a small boy who had been electrocuted.

“I never met Vann Nath but found his work very affecting.”

“He was important because the youth of today don’t learn about the genocide – it’s ridiculous that kids overseas learn more about it than they do here. So he was an educator in that way.”

Architect, photographer and painter Thang Sothea said he took great inspiration from Nath.

Sothea also depicts S-21 in his series of abstract “mosaics” in Seyha, Lost in Tuol Sleng.

“His work is a historical document…where as mine is my own interpretation … The young people need the past to guide the future,” he said.

The tribute, which starts this Saturday and will run until February 12, will feature the paintings, photos, sculptures and poems of 23 artists who have been inspired by Nath, who died in 2011.

Taking place at Bophana and organised by the French-run Vann Nath Friends Circle, the exhibition will be a catalogue of sorts, said President Yvon Chalm and a reflection on his life by many who were close to him, such as Karay’s You Lose My Memory, a portrait painted shortly after meeting Nath.

Chalm met Nath in 2008 and was deeply moved by his strength and determination.

“He spoke so openly about his story, and he had no anger, which was remarkable. The last five years he was very much involved in justice at the KRT, without any anger… He was so articulate,” he said

Sculptor Sopheap Pich met Nath in 2005, and donated a piece from his recent collection of reliefs’ a small square charcoal on burlap rattan grid.

“He was very open, I thought he may be bitter after enduring that, but he was quite the opposite. We spent a lot of time together in his studio … He said he had to keep creating and painting so that the memory would never fade,” he said.

To contact the reporter on this story: Claire Knox at [email protected]