Mong says the triad boss trusted him so much, in fact, that “he asked me to help him write his autobiography”.

The notorious Hong Kong crimes that inspired Chief Editor Detective novels

But eventually the law caught up with Wan, and by the time he was released from jail in 2012, Wan told Mong he no longer wanted to be in the spotlight or for his story to be told.

And so Mong, with a wealth of tantalising anecdotes and encounters with criminal big shots to draw from, turned to writing fiction two years ago. Last month he published the first of six planned books covering 20 crime stories based on his work as a journalist.

The stories in his Chinese-language Chief Editor Detective series are first-person dramatised portrayals of the sensational crimes Mong covered as an investigative reporter, including the escapades of “Big Spender” Cheung Tze-keung, who was involved in the kidnappings of tycoon Li Ka-shing’s elder son, Victor Li Tzar-kuoi, and Walter Kwok Ping-sheung, former chairman of Sun Hung Kai Properties.

Mong began his career at daily newspaper Ming Pao in 1972, working under the newspaper’s founder, Louis Cha Leung-yung, famed for the wuxia novels he wrote under the pen name Jin Yong. He later joined Sing Pao Daily News, before switching to racy magazines Oriental Daily and Next. His last media position was chief editor at East Week.

That was the start of a dark period for Mong, however. In 2002, the magazine was engulfed in scandal after publishing naked photos of Hong Kong actress Carina Lau Ka-ling taken years earlier during a kidnapping ordeal.

The images led to outrage and public demonstrations. Facing a barrage of criticism, East Week’s owner, Emperor Group chairman Albert Yeung Sau-shing, closed down the magazine. The title was later bought by the owners of Sing Tao Group.

Mong was sentenced to five months’ imprisonment in 2009 for distributing obscene articles. Reluctant to dwell on the episode, he says he doesn’t want it to eclipse his three decades of journalistic work.

“Although I’ve left the industry, I always reminisce about the big cases I covered. As I wrote [my novels], I retraced the investigative process again; how I interviewed the police, followed up leads, contacted my sources.”

Mong says working on the crime beat was a dangerous job. “Our investigative team didn’t work in a publication’s regular office. We rented a secret place. There was a steel office door for extra protection.

“I once ran into a triad boss in Taiwan whom I had previously exposed in an exclusive story. He accosted me and wanted to know the identity of the snitch who fed me the information. I told him it was a reporter’s responsibility to protect their source. He was okay in the end and acknowledged that what was written about him was true and I hadn’t framed him.”

It takes determination, tenacity and keen social skills to be a good crime reporter, Mong adds. “I knew thousands of policemen. I had to socialise with them, which can be time-wasting. I had to earn their trust for them to feed me information. Sometimes, it was a trade-off. For example, they might want something published to help them get a promotion, but it was of no news value. I would help them get it published as a favour, to be repaid later.”

Snooping on the wireless communications of police, firefighters and ambulance crew – the stock-in-trade of crime and accident reporters – became impossible in 2004 when government service communications went digital. Mong says that for this reason there are fewer explosive crime stories in newspapers today.

“We had people on 24-hour standby listening to communications. We had to know all the codes used, like for example ‘bird’s nest’ meant ‘airport’.”

Now the media does not follow major crimes as well as before, exclusives have dried up, and gangsters don’t have the same high profiles they once did, he says.

“In the ’90s, a single issue of a magazine could sell 200,000 copies. There was so much advertising we didn’t have space for it all. Bosses paid 18 months’ salary plus bonus, so reporters fought tooth and nail for exclusives,” Mong says. “Now an issue only sells around 30,000 copies.”